The 2018 French Open has entered its ninth tournament day. In the fourth round of the men's singles, third-seeded Marin Cilic and Daniele Fognini had a five-set clash before the former U.S. Open champion won 6-4, 6-1/3, 6-7(4), 6-3. Del Potro, seeded 5, was in better form, knocking out John Isner 6-4 to reach the last eight of the French Open for the first time since 2012.

The third-seeded Cilic faces a challenge from Fognini, who is not a bad player on clay. Cilic, who leads with three wins and one loss, got off to a rather smooth start today, breaking early to lead 3-0.

However, Fognini then went on a three-game run to bring the match back to parity.

Both sides then held, with the Italian making more mistakes in the inevitable 10th game and Cilic seizing the opportunity to break for a 6-4 lead.

Entering the second set, the Croatian took full control, using strong baseline attacks to break Fognini's serve twice, and the third seed won 6-1 to take a 2-0 lead in the next set.

Two sets down, Fognini exploded in the third set, opening with a 4-1 lead. Although Cilic then recovered, the efficient Italian held his advantage to break back to set 6-3.

The fourth set was even, with Cilic using the first nine games to take a 5-4 lead. Fognini did not relent at the crucial moment, and after saving match point in the 10th game, he tied the score again.

Both men then saved and the match went to a tie-break. Fognini, who made a good comeback in the tiebreak, won 7-4 and the match went to a deciding set.

The first six games of the deciding set, both of them each secured a 3-3 tie. At this point, Cilic regained the upper hand, and he broke straight to lead 5-3.

At the end of the match, the Croatian kept up the good work, breaking again to win 6-3.

The fifth-seeded del Potro will face Isner in the Miami semifinals two years ago, when Isner successfully ended Argentina's 15-game winning streak on tour and finally won the most important title of his career.

Playing again on clay, both men quickly got into shape after the opening set, with the first six games tied at 3-3.

Isner made a series of errors in the seventh game, and Del Potro took the chance to complete the break, then held serve for a 5-3 lead.

Although the American recovered his first serve and recovered one set, Isner, who lacked the ability to shoot on clay, was unable to recover the disadvantage, and Del Potro took the lead 6-4.

The second set followed the same pattern as the first, with Isner breaking Del Potro in the seventh game after playing the first six games in a tie.

The experienced Argentine relied on that one break to take the next set 6-4.

The American held off two break points in the opening game of the third set, but Del Potro broke in the third game and then served out a love game to take a 3-1 lead.

The tenacious Isner did not give up, and the American, who had been trying to keep his serve, saved match points in the ninth game to tie the score at 4-5.

However, at the key moment, del Potro still weathered the test of equalization, and locked the victory 6-4 after an attack, and advanced to the last eight.