DELRAY BEACH, Fla. - Donald Young was once a prodigy. Ten years ago, just months passed his 16th birthday, Young became the youngest year-end world No. 1 junior. He had already won the Australian Open junior title, turned pro at 14 and played in the U.S. Open main draw.

But Young has struggled over the years since with his consistency. He has been maligned for choosing his parents, Donald Sr. and Illona, as his coaches rather than those designated by the U.S. Tennis Association, and has failed to win a title on the ATP Tour.

Young will finally have the chance, just the second of his career, to play for an ATP title. With a 4-6, 6-4, 6-2 semifinal victory over Australia's Bernard Tomic on Saturday, Young reached the Delray Beach Open final. In his only other final appearance, in Bangkok in 2011, he lost to Scotland's Andy Murray.

Young will face fourth-seeded Ivo Karlovic of Croatia, a 6-3, 6-4 winner over fifth-seeded Adrian Mannarino of France. At a week shy of his 36th birthday, Karlovic, the 2010 runner-up, is the oldest finalist in the 23-year history of the tournament.

Against Tomic, Young hit eight double faults in the swirling wind — two in a row to lose his serve in the fifth game of the first set--but he also saved seven of 10 break points, including two at 4-4 in the second set, another while serving at 3-1 in the third and two more to hold for 5-2.

"I took a two-hour nap before the match and woke up irritated," said the 25-year-old American, who admitted that he was bothered by everything from the way a ball boy handed him his towel to the engine-revving of a courtside promotional car. "Usually those days don't turn out too well."

But instead of panicking, Young revved his own engine, fired forehands deep to Tomic's backhand, and stormed the net, hitting a bevy of stab volley winners.

Tomic had 13 aces and many more service winners, but Young had to rely instead on his foot speed and his guile, both of which are vastly improved this year.

Up 5-2 in the third, the 56th-ranked Atlanta resident pushed Tomic to 15-40 with a sneak-attack forehand volley winner. After Tomic saved a match point with a 117-mph ace, Young claimed victory when Tomic punched an unforced forehand long.

Young is 10-3 on the season, the best start of his career. Last year, he did not win 10 tour matches until mid-June. With a win Sunday, he will likely rise back into the world's top 40, close to his career-high No. 38 in 2012.

Against Mannarino, Karlovic served 17 aces, including one on match point, and he saved all five break points he faced in the second set. Karlovic has served 78 aces in four matches and hasn't dropped serve all week. He has held 47 consecutive times and been broken just four times in 13 matches this season.

Also Sunday, Bob and Mike Bryan, the world's No. 1 doubles team for the last six years, will play for their 104th doubles title.

The 36-year-old twins, winners of 16 major championships, reached their 155th career final with a 4-6, 6-3, 10-4 victory over fellow Americans Eric Butorac and Rajeev Ram. They will face second-seeded Raven Klaasen of South Africa and Leander Paes of India. Klaasen and Paes beat Tomic and Viktor Troicki of Serbia 6-4, 6-4.