Eight years, three trades and one toe operation later, he's doing it again.
Harris is even the leading scorer for Dallas - yes, ahead of Dirk Nowitzki - with the first-round series tied heading into Game 3 on Saturday.
''It's why I wanted to come back, to be in this type of situation and play in these types of games and be in this type of series,'' Harris said. ''It's perfect.''
Harris was in his second season in 2006 after the Mavericks traded up to get him with the fifth pick in the 2004 draft. His first career playoff start was Game 2 of the second round against the top-seeded Spurs, the first of three straight Dallas wins.
The speed of Harris gave the Mavericks something they lacked in trying to keep up with Parker, and they pulled the upset in seven games on their way to the NBA Finals for the first time in franchise history. Dallas lost to Miami in six games.
Fast forward to this week, and Harris led the eighth-seeded Mavericks with 19 points to put them in position to win the opener before the team went cold late and lost. He had 18 points in a Game 2 win, outscoring Parker by six.
''He's been great,'' Nowitzki said. ''He's a big key for us off the bench. We don't have a lot of penetrators out there. He's been great on both ends of the floor.''
Harris went to New Jersey in a 2008 trade for Jason Kidd, who was the point guard for the franchise's first championship when Dallas won a rematch with the Heat in 2011. The Nets shipped him to Utah in another deadline deal the year Dallas won the title, this time for Deron Williams. The Jazz sent him to Atlanta during the offseason in 2012.
When he finally had a chance to pick his own team, Harris agreed with Dallas on a three-year, $9 million contract that was scuttled after the extent of his toe injury was discovered, along with the need for offseason surgery.
Harris settled for a one-year deal for the veteran minimum of $1.3 million, then had a setback in his recovery and missed the first 41 games.
''We had to express some patience and just continue to work,'' the 31-year-old said. ''I knew at some point I'd be able to get back. I just didn't know when.''
The Mavericks have another speedy, penetrating guard in Monta Ellis, and Harris doesn't have to carry much of the defensive load trying to keep Parker out of the lane. Most of that duty has fallen to Shawn Marion so far.
But without Harris, the Mavericks would be counting on rookies Shane Larkin and Gal Mekel to relieve Ellis and starting point guard Jose Calderon.
''Right now it's winning time and you love experience,'' Nowitzki said. ''As good sometimes (as) youth and freshness is and young legs, experience is a big key too.''
Parker was the spark behind fast starts in the first two games of this series, but he finished Game 2 with just 10 shots despite Marion basically giving him the jumper by going under the screen on pick-and-roll plays most of the game.
He's had fewer shots than that just four times in the playoffs in the past 10 years, and says coach Gregg Popovich noticed.
''I felt like I was doing good but at the same time I wanted to get my teammates involved,'' Parker said. ''Pop told me if I have to shoot 25 times, I have to shoot 25 times if that's what they're going to give me.''
Even if they're not matched up, Harris and Parker will be measured up after each game. There's something about that series eight years ago - and what Parker said two years later when Harris was sent to the Eastern Conference.
''When I was here before he was happy to see me go,'' Harris said after Game 1. ''I'm looking forward to just matching up with him again.''
The Mavericks will need him if they're going to pull another upset.
Follow Schuyler Dixon on Twitter at https://twitter.com/apschuyler