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The second leg of the UEFA Champions League quarter finals begin on Tuesday on Paramount+ with four teams firmly in control after last week's matches. Chelsea, Paris Saint-Germain, Real Madrid and Manchester City all hold leads from the first leg and each of them are favorites to reach the semifinals. That doesn't mean that the quarterfinals are over, however. The Champions League has a penchant for providing thrilling comebacks.

But which team has the best chance of overturning their first leg deficit? Read on to find out:

4. Porto

At Chelsea, trail 2-0

Of all the quarter final ties this feels the nearest to being done and dusted. Porto have proven already in this campaign that European giants would do well not to take them for granted but they have such a sizeable gap to make up against Chelsea that the Blues could arguably afford to slacken off an iota and still reach the semifinals.

The reality is that Thomas Tuchel will not allow his team to do that anyway and will be preaching to them warnings of what Porto can achieve with their two top scorers, Sergio Oliveira and Medhi Taremi, available once more after missing the first leg through suspension. With or without those two it is still fair, however, to question whether Porto have the attacking punch to score the two goals they need to have any hope of progressing in this tie.

Of the remaining teams in the competition no-one has a lower expected goals (xG) tally from their nine games than Porto, who have taken shots worth a combined 12.74 xG. In part that figure is rather spoiled by two games against Manchester City where they created shooting opportunities worth 0.31 xG, but equally Porto are not a team that create a huge weight of opportunities for themselves. No one in this competition has taken fewer shots or scored fewer goals and many of the chances they have created have been headers that Chelsea are well-placed to deal with through the likes of Kurt Zouma, Antonio Rudiger and Andreas Christensen.

Champions League opponents have found it exceptionally hard to get into the Chelsea box since Thomas Tuchel's appointment TruMedia

Meanwhile at the other end Chelsea have the sort of options in their frontline that are well-placed to exploit any game situation. One might assume that this would be a game well suited for Kai Havertz, who excelled in a false nine role with runners ahead of him including Christian Pulisic, Callum Hudson-Odoi and Mason Mount, to orchestrate counter attacks picking out dangerous attackers. Porto will naturally have to push up as they chase victory but neither Pepe nor Chancel Mbemba are especially well suited to defending space in behind.

It has not been Chelsea's plan for most of their games this season to play on the break and they will surely still look to dominate possession -- only once in 15 league and European games under Tuchel have they had less than 50 percent of the ball -- but they have shown a willingness to adapt so as to exploit opponent weak points, as was the case when Timo Werner tore through Liverpool's high line in early March. The Blues might be one of the toughest opponents to face in Europe right now and Porto look a long way from being able to extend their European run.

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3. Borussia Dortmund

Home vs. Manchester City, trail 2-1

They may have a smaller deficit to overcome than some of those ahead of them in these rankings but they also have the toughest opponent of any left in the competition. Manchester City are favorites at +175 (odds courtesy of William Hill sportsbook) to lift the trophy in Istanbul for a reason, they are blending the best defense in Europe (the combined xG tally of their opponents in 9 games is just 3.34, more than 50% less than any other team still standing in the competition) with an attack that has a host of ways to beat opponents.

In our preview of the first leg we noted that City are exceptional at taking away the close range shots that Erling Haaland invariably converts and they did so for much of the first leg, though the way Ruben Dias bounced off the Norwegian before he shot against Ederson's leg in the 48th minute was a reminder that exceptional offense can on occasion trump even the most disciplined of defenses. The City goalkeeper saved that effort and was handed a reprieve when Jude Bellingham picked his pocket and saw his goal ruled out for a non-existent foul.

Defensively City were some way off their best while in attacking terms they were rather underwhelming, particularly in the period between Kevin De Bruyne's opener and Marcos Reus' equalizer, over an hour of football where only Phil Foden had any chances of note, logging 0.71 of the 0.94xG they created in that period. Games without a traditional striker have often seen Pep Guardiola's side at their very best this season but last week they were stodgy and lacked someone to stretch play into the spaces behind the Dortmund defense.

Yet, for all those difficulties nobody could really argue that a disappointing City performance merited anything less than a win. This team do not need to play at the peak of their powers to beat a Dortmund side who have shown plenty of defensive vulnerabilities this season, conceding 52 goals in 37 games across the Bundesliga and Champions League. The first leg ought to have served as a wake up call for Guardiola's side, that it did with them still coming away with a lead is testament to the quality of this team.

2. Liverpool

Home vs. Real Madrid, trail 3-1

It is hard to not believe in this Liverpool side even if this tie looks a step beyond them. A relentless force of will has been perhaps the defining trait of Jurgen Klopp's tenure and this is a team that does not know when they are beaten. At their best over recent years there has been a virtuous cycle between player, manager and fans, each propelling the next to ever greater levels of confidence and certainty.

Aside from the injuries, this season has served as an intriguing experiment in what happens when one of those links is removed. So while one does not have to cast one's mind far back to remember Liverpool overcoming an even greater deficit on Merseyside, beating Barcelona 4-0 in the second leg after losing the opener 3-0, the circumstances of Liverpool's task are dramatically different. If Georginio Wijnaldum heads one home in front of the Kop on Wednesday night he will have not have thousands of supporters with whom to share his jubilance.

Fortress Anfield is not what it was in the past and while there are specific footballing reasons why Liverpool are not as dominant on their home ground as they once were, there is an emotional power that has been lost from this team.

After the first leg defeat in Valdebebas, Klopp acknowledged as much: "If you want to have some emotional memories, then you watch the Barcelona game back and 80 per cent of this game was the atmosphere in the stadium. 

"So, yes, we have to do it without that. But it is not that I sit here and think, 'Comebacks are our thing, we do it all the time.' We did from time to time but we always had supporters in the stadium. We don't have that this time so I don't know if we can do it, but I can promise you we will give it a proper try."

Liverpool will surely improve on a first leg where they gave Toni Kroos the run of the Estadio Alfredo Di Stefano, failing to press Real Madrid's midfield while maintaining a high line. There are factors that Klopp can improve or mitigate but ultimately he cannot change the fact that he has two inexperienced center backs in Ozan Kabak and Nathaniel Phillips who will be facing off against Karim Benzema and fast runners in behind such as Vinicius Junior. It is hard to see how that does not lead to at least one Madrid goal, setting a bar too high even for this Reds team.

1. Bayern Munich

At Paris Saint-Germain, trail 3-2

A ludicrous first leg in Munich last week may well have been enough to kill off the tie, particularly as there are few teams better suited to ripping apart opponents on the counter than one containing Neymar and Kylian Mbappe. But if the second leg were to play out as the first did -- unlikely as it might be that there is a repeat of the blizzard of goals and, well, snow at the Allianz Arena last week -- there is no reason why the holders should not make it through to the last four.

Bayern Munich's shots against PSG with bubble size reflecting the xG of each effort TruMedia

Just look at that shot map above. Two big chances were converted but a remarkable four were missed by Bayern Munich: Leon Goretzka, Eric-Maxim Choupo Moting, Thomas Muller and Benjamin Pavard to be precise. In European and Bundesliga games over the past two years the German champions have had 14 games where they have created six or more big chances, they have won all bar one of them, scoring 62 goals and at least two in every game. Their xG last week was higher than it had been in crushing wins over Atletico Madrid and Chelsea over the years.

While they were profligate at one end -- and Keylor Navas customarily excellent in goal -- Bayern were clumsy at the other. A goalkeeper of Manuel Neuer's quality rarely spills a shot like Mbappe's into his own net. Allowing Marquinhos to drift in behind their defensive line was unforgivable even if Neymar's pass to find him was outstanding.

Bayern know they have the quality to beat PSG and to do so rather comfortably. Ligue 1 serves as a near weekly reminder that Mauricio Pochettino's side is not a vintage blend and that you do not need Robert Lewandowski to beat them.  Though on the other side of the ledger, the nature of the contest suits the French side, as according to Opta only their opponents attack with greater direct speed in the Champions League than Mbappe, Neymar and company. When you have forwards of that quality you might only need one big chance and ought to be considered favorites for the tie.

Still the first leg proved that Bayern have the quality to create chances. If they do not let so many pass them by at the Parc des Princes they may well find themselves in a semifinal against Manchester City.