NEW YORK (AP) Asked about the U.S. Tennis Association trying to find the ''next Donald Young,'' the former teen prodigy couldn't help but quip: ''I thought they moved on from me.''

Back in the second week at a major, Young can find humor in all those times his career was written off. If it seems as though he's been around forever, he has - it's been more than a decade since he played his first pro event. But at 26, he's still youthful by the standards of today's men's game.

''I never really forgot the fact that when I was 19, I wasn't going to be good ever. When I was 15, I was supposed to win Wimbledon the next year,'' Young said.

''I'm here now. I'm 26. I'm right in the thick of things,'' he added. ''That's when a lot of people start to play well.''

Consider Young's upcoming opponent in the fourth round of the U.S. Open. At the age of 28 1/2, Stan Wawrinka had never been to a major final; now he's won two Grand Slam titles in the last 20 months.

For long stretches of his matches at Flushing Meadows this week, Young has looked like a player whose best tennis is yet to come, pairing his creative shot-making with much-improved conditioning and mental fortitude. On Saturday, he came back from two sets down for the second time in three rounds.

And yet there have been these tantalizing moments before that proved to be blips instead turning points. Take the one previous time Young made it to the fourth round at a major, at the 2011 U.S. Open. He upset Wawrinka, then ranked 14th, in the second round that year, rallying from down two sets to one.

Not long after that, Young went six months without winning any match, losing 17 in a row.

''I've been beat up. I've beat up myself,'' he said. ''I've been down. I've had good times, bad times. Just some resilience and fighting. Hopefully it's not over and there's more to come.''

His ranking has never been better than 38th, not good enough to earn a seed in a Grand Slam draw. But if there's reason to believe this time is different, start with this fact: Before Tuesday, Young had been 0-17 in his career when dropping the first two sets.

Now he's made that comeback twice in five days.

In the first round, the 68th-ranked Young was down two sets and a break against 11th-seeded Gilles Simon. Then on Saturday, he failed to win a game in the second in falling behind by two sets to 22nd-seeded Viktor Troicki. With a raucous crowd at the cozy Grandstand willing him on, Young went on to win 4-6, 0-6, 7-6 (3), 6-2, 6-4 in 3 hours, 33 minutes.

He also dropped the opening set in the second round before winning in four.

Young was frank that those wouldn't have happened in previous years.

His conditioning, he acknowledged in an on-court interview, ''was a weak point for most of my career.''

''It was something you have full control over,'' he added, ''so I wasn't going to let that hold me back anymore.''

And in the past he never even gave himself a chance to complete such a comeback.

''I've kind of had a lot of times when I didn't fight,'' he said later. ''I've done that. Why keep doing that? Do something else.''

Wawrinka, who's seeded fifth, has noticed.

''He improved a lot. Especially his attitude on the court, he's fighting way more,'' Wawrinka said. ''He's always trying.''

After winning just 13 points in the second set, Young received treatment on his back. He said afterward it needs to be adjusted occasionally, though his opponent suspected gamesmanship in Young limping around the court and calling for the trainer. Troicki insisted he wasn't upset because all that is completely within the rules.

''He messed me up,'' Troicki said, ''and started playing better and better.''