ATLANTA — Quinton Stephens was an unlikely hero for Georgia Tech on Saturday.

The junior forward played only three minutes against Pitt in Georgia Tech’s last game, but he learned the next day he would be in the starting lineup against No. 4 Virginia. He took advantage of his first ACC start and responded with perhaps the best game of his career.

Stephens scored 16 points, including two crucial 3-pointers in the final four minutes, to help Georgia Tech upset No. 4 Virginia 68-64.

“Q made us look good,” Georgia Tech coach Brian Gregory said. “This is to his credit; he didn’t play much in the last game, and nowadays kids would be so broken and not be happy and all that stuff. Obviously he gave us a huge lift, made those two big threes, had really good execution on our set plays, and it was probably the difference in the game.”

The forward was 6-for-8 from the floor and 4-for-4 on 3-pointers, and he added five rebounds and an assist to help the Yellow Jackets avoid an epic second-half meltdown.

“It was all about confidence really,” Stephens said. “We felt comfortable with one another, we liked the group. I was really looking forward to the opportunity and tried to make the most of it.

Virginia had methodically erased an 11-point halftime deficit and tied the game 49-49 when guard Marial Shayok made a 3-point basket with 6:04 left.

Georgia Tech called timeout and emerged from the break to score 11 unanswered points, getting two 3-pointers from Stephens and another from guard Adam Smith to take a commanding lead.

“Funny thing: Once it was 49-up, all of us had smiles on our faces,” Stephens said. “In the timeout, we were like, ‘OK, if they want to make it a game, let’s make it a game. We came out and did what we had to do, made a little cushion and were able to knock down some free throws.”

It marked Georgia Tech’s first win over a Top 5 team since it beat Duke in 2010. It was the school’s first win over a Top 25 team at McCamish Pavilion since it opened in 2012-13.

“Our wins against Georgia, for me, are always big,” Georgia Tech coach Brian Gregory said. “But outside of that, this was by far our biggest win. We’ve got some big wins, but they’ve been on the road. But I think our guys went into the game expecting to win the game.”

Georgia Tech (11-5, 1-2 ACC) broke a two-game losing streak and beat a ranked team for the first time since it defeated Miami a year ago.

The Yellow Jackets also got 16 points and six rebounds from Smith, and 16 points and six rebounds from forward Nick Jacobs.

Virginia (12-3, 1-2) lost its second straight game. The Cavaliers were led by guard Malcolm Brogdon, who scored 15 points, and guard London Perrantes, who added 13. Forward Anthony Gill had 11 points before fouling out.

“We’re in for a fight,” Virginia coach Tony Bennett said. “We’ve got to improve. We’ve got to find a higher level of quality from start to finish. These guys have won so many games, and it doesn’t always just happen. You’ve got to battle for everything.”

Georgia Tech’s defense was outstanding in the first half. The Yellow Jackets held Virginia to 38 percent shooting, outrebounded the Cavaliers 21-12, and often forced them to work deep into the shot clock.

The Yellow Jackets got back-to-back 3-pointers from Smith and Stephens to take a 15-7 lead with 12:40 left.

Georgia Tech stretched the margin to 15 points when Smith made a 3-pointer with 1:15 to give his team a 33-18 lead. Georgia Tech led 35-24 at halftime, handing Virginia its largest halftime deficit of the season.

Brogdon provided the only real offense for the Cavaliers with 11 points. Stephens had 10 and Smith scored nine for Georgia Tech, which shot 48 percent, and led 35-24 at the half.

“Credit to Georgia Tech,” Bennett said. “They’ve got a better team. They’re much more balanced inside-out this year and that was an issue. Whenever we got it close, they hit a couple big shots.”

NOTES: The game was the first sellout of the season at Georgia Tech. … Georgia Tech started James White at forward in place of Nick Jacobs, who had started the last three games and 13 of the previous 15. The Yellow Jackets also started F Quinton Stephens in place of PG Josh Heath and slid Adam Smith to the point. It was Stephens’ first start of the season. … Virginia started Marial Shayocck instead of Isiah Wilkins at guard. Wilkins had started the previous five games. … Three Virginia players from the Atlanta area were making returns home: Wilkins and G Malcolm Brogdon, who both played at Greater Atlanta Christian School in Norcross, and reserve F Evan Nolte, who played at Milton High. … Virginia, which has played two straight road games, returns home for its next game on Tuesday against Miami. Georgia Tech hits the road again on Wednesday to play Notre Dame.