Canada's Frank Dancevic fought for more than three and a half hours before losing a marathon to Joao Sousa 7-6 (6), 3-6, 6-2, 4-6, 7-6 (2) to exit in his opening match at the U.S. Open on Wednesday.
It was the first five-set match for the Niagara Falls, Ont. native since 2011 Wimbledon.
"It was a heartbreaker, it's tough losing matches like that," said Dancevic, who played with a new racquet model for the first time during the match, "It could have gone either way. It was one of those that came down to a few points."
Portugal's Sousa, ranked 38th, finally moved into the second round in the final-set tiebreaker, as he smashed back a weak Dancevic defensive lob to secure the win.
An exhausted Dancevic, ranked 135th, finished the battle with 50 winners and 51 unforced errors, pounding down 17 aces and converting on four of 14 break chances.
"When I was down 5-2 in the fifth set it looked like he was getting tight when he served for it at 5-3. I got back into the match but not quite enough.
"We played really good tennis. It's unfortunate that I lost, but I feel really good about my game. ... I feel good physically. If I keep this level up I can do some damage the rest of the year."
The Dancevic defeat leaves fifth seed Milos Raonic, from Thornhill, Ont., as the last Canadian left in the men's competition. Wimbledon finalist and seventh seed Eugenie Bouchard, from Westmount, Que., is into the second round in the women's draw.
Dancevic had chances to seize the early lead at the end of the opening set, when he found himself with five set points. But Sousa chipped away at the deficit to eventually win it.
The 29-year-old stepped up his game to claim the second set, but then lost the third to trail two sets to one.
In the fourth, Dancevic regained the momentum — losing a break for 4-4 but getting it back a game later to lead 5-4. He squared the match at two sets each with a backhand pass.
The fifth set provided the most dramatics as Dancevic fought back from down 2-5, forcing another tiebreaker. But luck ran out for the Canadian as Sousa found a finishing burst to advance.
Dancevic said that he had to modify his strategy during the match as he had only two frames of the new racquet at his disposal.
"I made the chance a few days ago, I think I played exceptionally well considering it was a new racquet and completely new strings. For me it's a whole new approach to the game.
"I've trained well with it but I was unsure in some key moments. I like it though and will stick with it until the end of the year."