For the first time this season, University of the Philippines faced a serious test.

But the Fighting Maroons displayed tremendous grit, maturity and character down the stretch to pull off a thrilling 80-76 overtime victory over Far Eastern University to stay perfect in Season 86 University Athletic Association of the Philippines men's basketball tournament on Wednesday at the Mall of Asia Arena.

Meanwhile, defending champion Ateneo de Manila University completed a 74-69 win over University of the East in the second game.

Kai Baluggay led the Blue Eagles with a double-double game of 18 points and 11 rebounds while Joseph Obasa scored 16 points on a 4-of-7 shooting clip as they are tied with the Red Warriors at fifth place with similar 2-2 records.

Rookie Lebron Lopez and Malick Diouf shone in the extra period as they scored six straight points to help the Fighting Maroons claw their way back from a 71-73 disadvantage and coast to their fourth straight victory in the country's most prestigious collegiate league.

Although the Tamaraws threatened to make a final stand off a three-pointer by Jorick Bautista in the final 30.3 seconds, 76-77, CJ Cansino split his charities before rookie Janjan Felicilda iced the game with a layup in the final seven seconds.

UP assistant coach Christian Luanzon said their goal is to gain momentum by racking up as many wins as they can in the first round.

"Well, it's good for us as coach Gold (Monteverde) said last game that it's always nice to gather as many wins as you can," said Luanzon, whose squad is enjoying its finest start since going 4-0 in 1997.

"One thing I have seen in the UAAP as an advantage is that if you're able to get at least five or six wins early under your belt, it's a big advantage coming into the second round."

"So, it's a big deal and what coach Gold would always say, every game is a chance to grow and hopefully as we continue to grow, it translates into wins."

Felicilda delivered 17 points on a sizzling 6-of-7 shooting from the field on top of four rebounds and two assists while Diouf dropped a double-double of 11 points and 20 rebounds for the Fighting Maroons, who are looking to regain the crown that got knocked off their heads by Ateneo last year.

Lopez, for his part, also flirted with a double-double, scoring nine points and 11 rebounds while Cansino chipped in 14 markers.

After an impressive off-season preparation, the Fighting Maroons opened their campaign on a sizzling note as they crushed Adamson University by 17, 68-51; UE by 15, 84-79; and National University by 18, 78-60.

But against the Tamaraws, the character of the Maroons was severely tested.

After leading by as many as eight points in the first period, 17-9, UP was threatened when Jorick Bautista knocked down a three-pointer to tie the count at 68 with only 30.3 seconds left in regulation.

Harold Alarcon tried to put the Maroons back on top but he missed his jumper in the final 11 seconds.

UP had one last chance to escape with the win after the Tamaraws committed an error, but Diouf was called for interfering with the made basket by Lopez as time expired to send the match into extra period.

"As coach said, we have to be ready for whatever situation — either easy or difficult," Felicilda said.

"We always have to overcome different kinds of challenges."

Bautista fired a career-best 26 points on 6-of-6 shooting from the three-point area while Gonzales delivered 19 points, nine rebounds, four assists, and two steals for the Tamaraws, who played without Cholo Añonuevo who fractured his right hand.