Second-seeded Adrian Mannarino shook off a second-set lapse to beat Jordan Thompson 6-0, 6-7 (7/4), 6-2 on Thursday and set up an all-French semi-final against Ugo Humbert at the ATP grass court tournament in Newport, Rhode Island.

Mannarino was rolling at 6-0, 5-2 but ended up laboring for almost three hours to make his way into the final four.

"I was just trying to stay focused, to play every point like I should do, not getting upset from the scenario of the second set and trying to stay consistent," Mannarino said, admitting in his on-court post-match interview that he "choked" in the second set.

"I was up so far in the score, and then Jordan started to play really well. He was not missing any more and in the beginning of the third set he had the (momentum).

"So it was tough to stay in the match, but I did it very well."

Thompson, who is playing doubles with Mannarino this week, won four straight games to swing the second set his way.

He had an early break chance in the third, but Mannarino managed to fend him off and reestablish control.

The French veteran next faces third-seeded compatriot Humbert, who defeated South African Kevin Anderson 6-2, 6-4.