The first match of the day in the Next Gen Arena, saw the unseeded American John Isner battled past sixth seed Marin Cilic in three sets at the Internazionali BNL d'Italia. The former world number nine trailed 1-6 in their head-to-head. However, Isner defeated the 2014 US Open champion in their last encounter in the semifinals at the BNP Paribas Masters in Paris, last November. 

Isner's victory over Cilic means that he will play in his first Masters 1000 semifinal on clay, and becomes the first American since Andy Roddick in 2008 to reach the semifinals at the Foro Italico. Isner will play against 16th seed Alexander Zverev for a place in Sunday's final at the Foro Italico.

Isner wins a marathon opening set

The 32-year-old American opened proceedings in this quarterfinal encounter in the Next Gen Arena, and it was comfortable service game to lead 1-0. The Croat followed suit with a comfortable hold to level the match at 1-1. Once again, the world number 24 remained untroubled in his next service game to lead 2-1. However, the duo was engaging in baseline rallies, and the duo went to deuce, five times in Cilic's second service game. Furthermore, the 2014 US Open champion held serve, snuffing out Isner's attempt with a forehand down the line, cutting it out with a sublime half-volley at the net to level the set at 2-2.

The big-serving American held comfortably in the fifth game, and Cilic produced a couple of forehand winners down the line, followed by a backhand winner and a big serve out wide, forcing the error from the two-time Masters 1000 finalist, to hold to love and level the opening set at 3-3.

Cilic was looking to break the unseeded American in the next game with a scorching backhand winner down the line. However, Isner's big serving with an ace down the T came to his rescue, and Cilic failed to punish Isner's weak second serve with an unforced error out wide. Furthermore, the sixth seed got the game at 30-30 with a passing shot down the line, with the net cord, helping him. Once more, Isner didn't panic with a big second serve, service winner down the middle, and a drop shot winner with Cilic firmly placed behind the baseline, gave the American to nudge ahead of the scoreboard in his favor at 4-3.

The Croat may have been disappointed to have lost this match but goes into the French Open with some confidence (Photo by Gareth Copley / Getty)
The Croat may have been disappointed to have lost this match but goes into the French Open with some confidence (Photo by Gareth Copley / Getty)

However, the world number 24 was looking to break Cilic's serve, as he would have the chance to serve for the opening set. He created his first break point chance with a brilliant running forehand passing winner down the line. Cilic quickly snuffed that out with a big serve out wide, targeting Isner's backhand and forcing the error. The Croat sealed the game with his first ace of the match to keep the match leveled at 4-4.

Both players remained untroubled throughout the remainder of the opening set, and an inevitable tiebreak ensued. The former world number nine began the tiebreak, and he led 1-0 by virtue of a Cilic unforced error. He quickly raced out to a 3-0 lead with Cilic putting in an untimely double fault. Nevertheless, the sixth seed got on the scoreboard with Isner coming out second best in a long rally, committing an unforced error. However, Isner built on his lead at 4-1 but Cilic won the next point with another unforced error springing from Isner's racquet. Unfortunately, for Cilic, he double-faulted for the second time in the tiebreak to give Isner an unassailable 5-2 lead. The Croat returned Isner's serve with intent to the American's feet, who struggled to deal with it. Furthermore, in typical Isner fashion, an ace down the T, brought up his first set point. The world number 24 took it at the first time of asking with a tame unforced error in the net from Cilic, gave Isner, the set 7-3 in 55 minutes. 

Cilic cruised in the second set to send the match to a decider

The sixth seed put the disappointment of losing the opening set behind him, starting the second set with a hold to love. He started this set with intent as he immediately broke Isner with a forehand winner to lead 2-0. He consolidated the break to love with a big serve out wide. Isner was a shadow of himself in this second set, as Cilic returned superbly at 15-40 looking for the double break. However, Isner's ninth ace of the match out wide saved the first break point that he faced, and he wiped out the second with a big serve out wide, and a forehand winner. A couple of more aces bailed Isner to keep the break at one but trailed 1-3.

Cilic started his next service game with a double-fault but won the next four points to extend his lead to 4-1. Once again, the former US Open champion was looking to get a double break advantage. Isner raced out to a 30-15 lead but Cilic won the next two points with a backhand winner down the line, ending the rally quickly for another break point. Isner's serve came to his rescue as he sent down a big serve to force an error from the Croat. A couple of backhand unforced errors, from Cilic's racquet, got Isner off the hook but was still trailing 2-4.

The former US Open champion dominated in the second set but was unable to take control of the final set (Photo by Tiziana Fabi / Getty)
The former US Open champion dominated in the second set but was unable to take control of the final set (Photo by Tiziana Fabi / Getty)

The sixth seed had a tougher time in his next service game but a service winner eventually sealed the game for the Croat who was one away from the second set. The American struggled to serve to stay in the second set, with a missed forehand brought up a first set point for Cilic. The 2014 US Open champion took it at the first time of asking by virtue of a wayward backhand unforced error from Isner to take it into a decider. 

Isner needs another tiebreaker to book his place in the semifinals in Rome for the first time

Both players had finally settled in this grueling clay court encounter at the Foro Italico. Cilic began the final set, and both players held their first couple of service games with one point being dropped by either player to their opponent with the final set nicely poised at 2-2. The final set remained served-dominated as expected with the match level at 3-3. However, in the Croat's fourth service game, he had faced a break point. He saved it with an unreturnable big serve out wide, followed by an ace down the T. However, the game went to deuce with a forehand sailing long. Nevertheless, the sixth seed sent down a big serve, followed by an unforced error out wide from Isner to lead 4-3 in this decisive final set.

The 32-year-old was under pressure in his next service game, and an 18th ace down the middle got the game to 40-15. A double fault quickly followed, and Cilic returned a good second serve from Isner to get the game to deuce. Once again, big serves from Isner got him out of the jail to level the second set at 4-4.

The Croat-held his next service game easily, and he was looking to win the match in the tenth game as he was two points away from victory. Isner didn't panic as he sent out a big serve out wide, followed by a forehand winner as part of a one-two combination, followed by an ace out wide, and a serve to Cilic's body gave him a game point. He took it with a big serve, forcing Cilic to place it in the net, and level the match at 5-5.

The former US Open champion remained untroubled on serve, serving it out to love, and Isner held in the next game to take the match to a final set tiebreaker.

Isner remained mentally strong in the final set (Photo by Tiziana Fabi / Getty)
Isner remained mentally strong in the final set (Photo by Tiziana Fabi / Getty)

Cilic began the tiebreak and he came out on top in the lengthy rally, and a gutsy forehand winner, just hitting the line gave him a 1-0 lead. Unfortunately, for the sixth seed, it went downhill as Isner won five successive points in a row with a couple of aces, and the wind picked up forcing Cilic to miss a smash. The Croat stopped the rot with a forehand winner in the corner but trailed 2-5. The next two points were on Cilic's serve but he failed to capitalize on it, as he committed an unforced error with his forehand breaking down to give Isner his first match point. The American took it with a tame backhand sailing in the net from Cilic to win the match, 7-6 (3), 2-6, 7-6 (2) in 2 hours and 37 minutes thriller.