New York: Defending champion Marin Cilic reached the US Open semi-finals on Tuesday with a 6-4, 6-4, 3-6, 6-7 (3/7), 6-4 win over France`s Jo-Wilfried Tsonga.
Over a four-hour battle on Arthur Ashe Stadium, the 26-year-old claimed a fifth win in six matches against Tsonga, firing 29 aces and 63 winners.
But the 30-year-old Tsonga made him work in 35-degree (95 F) heat, saving four match points before the champion went through.
Croatian ninth seed Cilic goes on to face either Serbian top seed Novak Djokovic or Spanish 18th seed Feliciano Lopez for a place in Sunday`s final.
He will be hoping Lopez prevails as he has a 3-2 career lead over the left-hander compared to a dismal 0-13 record against Djokovic.
"It was a big mental battle. I lost the fourth set despite having three match points. Jo played some amazing shots," said Cilic, who dashed Tsonga`s hopes of completing the set of semi-finals spots at all four majors.
"It was very hot, very demanding. I am proud that I stuck to my game plan and didn`t back down."
Tsonga, who had also made the quarter-finals in 2011, went into the tie having not been broken in 56 service games at this year`s US Open.
Cilic had to save four break points in the sixth game of the opener.
But it was the Frenchman who cracked first, his perfect serving run ending at 60 as Cilic converted on a fourth break point for a 5-4 lead on his way to securing the opener.
Cilic turned the screw again in the second set, breaking for 3-2 courtesy of a fifth double fault served up by Tsonga.
The Croatian was in complete control, sweeping into a two-set lead with Tsonga bedevilled by 14 unforced errors compared to his opponent`s five.
Just as tellingly, Cilic didn`t allow a single break point in the entire set.
Tsonga`s mood wasn`t helped by needing strapping applied to below his left knee at the changeover.
He looked doomed when he managed just three points off the first three Cilic service games of the third set, but suddenly shook himself out of his lethargy to win three games on the bounce to claim the third set.
Tsonga fought off two match points in the 10th game of the fourth set and another in the 12th.
The 30-year-old capitalised on his escape, sweeping the tie-breaker, topped off by a 13th ace of the contest.
But Cilic finished the fresher, breaking for a 3-2 lead and despite double-faulting on a fourth match point in the 10th game, he secured victory when Tsonga fired a forehand wide.
Djokovic, meanwhile, will be playing his 26th consecutive Grand Slam quarter-final as he continues his push towards a 10th major and third of the year after the Australian Open and Wimbledon.
Tuesday will represent his ninth successive US Open quarter-final slot while 33-year-old Lopez is playing in his first at the 14th attempt.
Lopez has lost all five times he has played Djokovic, winning just one set in their first meeting at the 2007 Australian Open.
Lopez knocked out Fabio Fognini, the conqueror of 14-time major winner Rafael Nadal in the last round.
Nadal`s shock exit was followed by an even more seismic event on Monday, when third seed Andy Murray was dumped out by Kevin Anderson in what was the 2012 champion`s earliest Slam exit in five years.