WASHINGTON -- Louisville coach Rick Pitino called it an "acrobatic follow-up."
Markel Starks, a guard for Georgetown, called it "unbelievable."
Whatever the description, a backward tip-in by reserve Aaron Bowen proved to be the winning basket as Georgetown handed No. 5 Louisville its third consecutive defeat, 53-51, on Saturday in a Big East Conference game.
Starks and Otto Porter Jr. each scored 17 points for Georgetown (14-4, 4-3 in the Big East).
Bowen's tip-in with 3:40 remaining gave the Hoyas a 52-50 lead and Peyton Siva of Louisville missed a shot in the final seconds with the Cardinals trailing, 52-51.
Those were the only points of the game for Bowen, who made one of three shots from the field in 15 minutes.
The Hoyas got the rebound of Siva's miss and Porter was fouled with 1.4 seconds left. He hit the first free throw before missing the second.
A desperation heave by the Cardinals (16-4, 4-3) fell short at the buzzer.
Porter added 12 rebounds for the Hoyas, who won the battle of the boards, 34-29, and won despite making 17 turnovers while shooting 38.8 percent from the field.
"We knew rebounds would win the game," said Bowen, a 6-foot-6 junior forward who entered the game with a career average of 1.4 points per game. "I kept trying to go in and get the rebound. I was blessed that it went in."
Said Starks: "I have never seen anything like it. He just came out of nowhere. It was unbelievable."
Bowen, who has never started in 34 college games, is hardly in the limelight and his cell phone went off in a post-game press conference with coach John Thompson III, Porter and Starks also sitting at the same table.
Thompson III laughed and pointed out that Bowen was not used to attending such interview sessions and turning off his cell phone after games.
Luke Hancock of Louisville, a transfer from nearby George Mason, returned to the area and had 12 points in only his third start of the season.
Russ Smith and Gorgui Dieng each had 12 for the Cardinals.
"Tonight we didn't get it done," said Pitino, who added that the Cardinals did not block out on the tip by Bowen. "We don't panic at Louisville. We are judged in March. All of college basketball is judged in March."
But Pitino added of hosting Pittsburgh on Monday: "It is a must game for us. We have to get after it."
Georgetown is 4-1 since Greg Whittington, the second-leading scorer on the team, has been out because of academic issues, according to the Washington Post. He was in street clothes on the bench Saturday.
"We might have been 5-0 with him," Thompson III said. "He is a loss, a big loss. We have people who have stepped up."
The Cardinals took their first lead of the second half on a 3-pointer by Hancock to make it 34-33 and he hit another 3-pointer to give Louisville a 37-35 lead with 16:33 to play.
But Georgetown took a 39-38 lead on a basket by Starks and two three throws by Porter made it 41-38 with 12:10 to go.
Siva, who had 13 assists on Tuesday at Villanova, was in foul trouble most of the game and picked up his fourth foul midway through the second half and wound up scoreless with two assists in 23 minutes.
"He is very fast, very quick," Starks said.
Georgetown took a 21-12 lead midway through the first half and led, 24-15, on a 3-pointer by Porter with 10:08 left in the first half.
But the Cardinals, who made their first 12 free throws, started getting to the foul line to get back into the game.
Smith hit two free throws to make it 27-21 and Louisville pulled to within 29-27 on two free throws by Wayne Blackshear with 3:58 left in the first half.
Georgetown led, 33-29, at halftime as Porter had 10 points. The Hoyas made all six free throws in the first half, while Louisville made all 12, including a stretch of 10 points in a row from the free throw line before a field goal by Dieng pulled the Cardinals to within 31-29 with 2:09 left in the half.
Smith, Louisville's top scorer, came off the bench for only the third time this season after he made only 2-of-13 shots from the field for eight points in the loss at Villanova on Tuesday. He was averaging 18.7 points per game before Saturday and had six points in the first half against the Hoyas.
The Cardinals, after 11 straight victories, were coming off back-to-back losses, at home to Syracuse on Jan. 19 and at Villanova on Tuesday, while Georgetown won Monday at Notre Dame.
Georgetown had scored 48 points or fewer in four of its games heading into Saturday.
The Hoyas were ranked in the top 25 earlier this season, but fell out of the poll after a 73-45 loss at home to Pittsburgh on Jan. 9.
NOTES: Louisville will host Pittsburgh on Monday, while the Hoyas host Seton Hall on Wednesday. ... The Cardinals made 34.8 percent of their shots and had only seven assists on 16 baskets, with 13 turnovers ... Georgetown has won the last two meetings against Louisville. ... Luke Hancock made 3-of=4 from 3-point range, while his teammates were 0-for 7.