With four double-digit seeds still alive and three No. 1 seeds facing challenges from well-seeded opposition, this weekend's Sweet 16 could bring some surprises. After all the unexpected outcomes the first two rounds of the NCAA Tournament provided, some more upsets could be on deck.

Most notably, Oral Roberts has a chance to make history. If the Eagles can knock off No. 3 seed Arkansas, they would become the first No. 15 seed to ever reach the Elite Eight. Such a result would constitute one of the most memorable Sweet 16 games of all time.

Seeing No. 1 seed Baylor fall against No. 5 seed Villanova, or seeing No. 1 seed Gonzaga lose to No. 5 seed Creighton might be just as shocking, though. The Bears and Bulldogs have been the most dominant teams in college basketball season and are favorites to reach the Final Four.

So as the action heats up again, let's reflect on some Sweet 16 history. Here are the most memorable games from this round since 1985. Perhaps by the end of the weekend, another will be added to the list.

2002: No. 10 Kent State 78, No. 3 Pittsburgh 73 (OT)

Kent State forward Antonio Gates -- the guy who later made eight NFL Pro Bowls with the Chargers -- muscled a shot up through defender Jaron Brown that appeared to give the Golden Flashes the lead with 25 seconds left. A whistle blew as the shot banked in, and it seemed for a second as though Gates would be heading to the free-throw line with a chance to complete a 3-point play.

But as Brown reacted in disgust at the whistle, the referee motioned for a jump ball. It was ruled that Brown had tied up Gates before the shot attempt, negating Gates' shot entirely and returning possession to Pittsburgh for the final possession of regulation. The Panthers failed to capitalize on the fortuitous call, however, and the game went to overtime. 

Pitt's Chevon Troutman and Kent State's Nate Gerwig battle during their 2002 Sweet 16 game. Getty Images

Ultimately, Gates rendered the snafu with the controversial call moot by scoring six points in overtime, including a pair of crucial free throws with 41 seconds left, to propel the Golden Flashes on to the Elite Eight. Not bad for a guy who ended up being a football player.

1990: No. 4 Georgia Tech 81, No. 1 Michigan State 80 (OT)

Chaotic hardly begins to describe the end of Georgia Tech's win over Michigan State in 1990. The Yellow Jackets trailed by four with just 13 seconds left when Kenny Anderson cut the deficit to two on a coast-to-coast lay-up with six seconds left. The Yellow Jackets fouled on the inbounds pass. Just one second elapsed from the clock, even though it appeared the Spartans' Steve Smith held the ball for much longer before the whistle.

Smith could have made that dispute irrelevant by making both free throws. Instead, it set the stage for another clock dispute. Smith, a prolific Michigan State scorer, missed the front end of a one-and-one. Anderson ended up with the ball for Georgia Tech and a chance tie the game or win it in the final seconds. He hit an off-balance 3-pointer right as the buzzer sounded. Or was it a 2-pointer? Or would it even count at all?

The Yellow Jackets rushed the floor and mobbed Anderson as one official held his arms up to signal a 3-pointer. But the officiating crew huddled together briefly and interrupted the celebration as Michigan State coach Jud Heathcote protested on the floor. They ruled that the shot came before the buzzer but that it was a 2-pointer. Overtime would be needed.

Michigan State led 80-79 in the extra period when Dennis Scott hit the go-ahead basket for Georgia Tech with eight seconds left. Ken Redfield's last-second heave bounced off the back of the rim and Georgia Tech escaped with the victory.

2019: No. 3 Purdue 99, No. 2 Tennessee 94 (OT)

The Volunteers and Boilermakers combined to shoot the same percentage from the 3-point line as they did at the free-throw line in a wild, fast-paced game that featured among its ingredients: an 18-point comeback, 3-point barrages from both squads, a battle of big men with an eight-inch height differential, last-second drama and overtime. Oh, and there were a total of 31 missed free throws.

Tennessee trailed by 18 early in the second half before roaring back to take the lead. But Purdue's Ryan Cline produced the game of his life with 3-pointer after 3-pointer -- hitting seven in total and four in the final 5:04 of regulation -- to help the Boilermakers stay in it.

A controversial foul call on a Carsen Edwards 3-point attempt with 1.7 seconds left sent the Purdue guard to the line with Tennessee leading by two. Edwards missed the first free throw but hit the next two to force overtime. Purdue pulled away in the extra period.

2013: No. 4 Michigan 87, No. 1 Kansas 85 (OT)

Trey Burke scored all 23 of his points after halftime, including five in the final 15 seconds of regulation, to lead the Wolverines back from a 14-point deficit. His deep, contested 3-pointer from the left wing with 4.2 seconds remaining in regulation forced overtime and might be one of the most underrated shots in NCAA Tournament history.

Michigan held on for the win when Kansas guard Naadir Tharpe's potential game-winner hit the backboard and rim before falling off at the buzzer. This was a pivotal moment on the Wolverines' path to their first Final Four of the John Beilein era. 

As spectacular and clutch as Burke was, teammate Mitch McGary was just as good. The freshman forward averaged just 7.5 points per game for the season. But he scored 25 on 12 of 17 shooting to help take down the No. 1 seeded Jayhawks.