The 24-year-old Camat bowed to a vastly superior Russian in Gaydarbek Gaydarbekov, 13-35, that dampened the bid of the Pinoy fighters at the Peristeri boxing hall here.
The 28-year-old silver medallist in the Sydney Games gave Camat neat lessons in four rounds, weaving in and out of the Filipinos range and firing clean shots on the run.
The reigning European titlist, seeded fourth in the division, displayed remarkable hand speed as he seized control early and piled up points that forced the Filipino fighter to abandon his game plan to land a big one to no avail.
Dionisio got off to a furious start in the first 25 targets, wavered in the next phase and recovered in the last 25 of the 75-target elimination round in the trap event at the Markoupoulo range.
The 32-year-old Dionisio missed only one claybird in the first canto to rank 13th but missed five in the next before recovering his form in the last stage for 24-20-23-67 and a 32nd in ranking.
He was seven birds behind the leading score of 74 by world champion Giovanni Pellielo of Italy and Alexei Alipov of Russia going into the final 50 targets today. The top six shooters after the elims will then shoot off in another 25 targets to determine the medallists.
The swimmers failed to take advantage of top-class opposition and missed the chance to improve on their personal best in the first day of the swimming events.
United States-based Miguel Molina lost his rhythm in the first 100 meters, rallied in the next but apparently spent himself from the effort as he finished eighth and last in his heat and 34th among 36 tankers in the 400-m individual medley.
Molina had a time of 4:33.25 in the second heat, way off the 4:23.26 best time he posted in the Vietnam SEA Games last year.
Sydney Games veteran Miguel Mendoza ruled his heat in the 400-m freestyle but could only end up 36th in the 46-man field. He had a 4:01.99 against his best time of 3:59.07 although his coaches said his performance augured well for his stint in the 1,500-m.
And rookie Timmy Chua also missed breaking his own mark in the 100-m breaststroke, finishing 50th among 59 bets in 1:06.37, two seconds off his mark of 1:04.93 made in the Hong Kong qualifying event last month. The top qualifier in the event, Japans Kitajima Kosuke, clocked in an Olympic record of 1:00.3.
"Karamihan sa mga swimmers natin mga first timers, kaya ninenerbiyos pa sila. But lets hope and see," said Chito Rivera, secretary-general of the Philippine Amateur Swimming Association.
It was a devastating loss for Camat who had labored for eight long years to get a crack at the Olympic gold and he gamely slugged it out for four rounds but the Russian was simply technically superior and talented for the Filipino.
Gaydarbekov raced to a 6-3 lead in the first round and 16-6 in the second and coasted to victory as the Fil-Am missed wildly from the third round on bidding for a killer blow that never came.
Camat continued to put the pressure on the Russian who responded with solid left and right hands and later tagged the Filipino with a short right. Although Camat looked like he had slipped, he was given a standing 8-count knockdown in the last 30 seconds.
Gaydarbekov completely dominated Camat in the fourth round, throwing rapid-fire blows as the Filipino struggled in a neutral corner for the second standing 8-count.
That left lightwelterweight Romeo Brin to put the Filipinos on track in their Olympic campaign as he goes up against Swedens Patrick Bogere.