Oconer of the Philippines Under-23 team emerged the photo finish winner with a time of one hour, 24 minutes and nine seconds for the 59.7-kilometer stage from Batangas City.
With the win, the son of former Olympian Norberto, a senior at Kalayaan National High in Kalayaan, moved 12 seconds behind overall leader Joel Calderon of Nueva Ecija.
Valenzuela of 7-11, the stage 4 winner, also moved up to third 1:37 behind the overall leader, who finished in the main pack along with Baler Ravina of East Pangasinan.
A scuffle between team captains Cris Joven of American Vinyl and Lloyd Lucien Reynante of 7-11 marred the race 10 km from the finish.
Officials later fined the two $200 each on top of a stern warning and a demand to issue a public apology.
The two vaunted climbers were leading the race after the lone King of the Mountain phase, some 800 meters above sea level, when they decided to settle their differences.
Joven claimed Reynante kept on nudging him and when he tried to get even, Reynante challenged him to a fight.
“He kept on doing that all race including in Calapan,” said Joven in Filipino. “When I nudged him back, he got off his bike first so I tried to hit him.”
Joven took a swing but Reynante deflected it with his bike.
American Vinyl coach and two-time champ Renato Dolosa quickly intervened and separated them. The two continued to exchange heated words before a stunned crowd who lined up the streets.
Oconer, Valenzuela, Calderon and Ravina took advantage of the incident to make a mad dash to the foggy finish line.
“I gave it my all in the last 700 meters. I said to myself it’s okay if somebody sneaks in, but I’m happy I got the stage win,” said Oconer, who also posted his fifth straight win in the under-23 division.
Foreign race officials led by chief commisaire Martin Bruins talked to Joven and Reynante and their respective team coaches after the stage and decided not to eject both riders.
Joven, 24, said he was disappointed by Reynante’s action. “He is my idol and I look up to him (Reynante), but now all my admiration is gone,” Joven said in Filipino.
Despite the incident, the 33-year-old Reynante, son of 1977 and 1980 titlist Maui, gained in the overall classification, moving up to 10th, 7:52 off the pace. Joven slipped from seventh to ninth, 7:36 off Calderon.
The race starts today from Quezon City to Tarlac City via the North Expressway.