NEWPORT, R.I. (AP) Americans Jack Sock and Rajeev Ram advanced to the quarterfinals of the Hall of Fame Tennis Championships on Wednesday.

Fourth-seeded Sock rallied past Lukas Lacko of Slovakia 3-6, 7-6 (4), 6-4. Ram defeated Yuichi Sugita of Japan 6-4, 6-3, a day after upsetting top-seeded John Isner.

The 31-year-old Ram returned the various slices, lobs and other change-of-pace shots offered by Sugita. The 161st-ranked Ram last won the Newport title in 2009.

The 22-year-old Sock, ranked 39th, needed two hours to advance in humid conditions on center court.

''You see a lot of upsets here every year, it's part of the game,'' said Sock, who faced seven break points, saving four in the third set. ''With the weather, I haven't been in much humidity and heat - that took some adjusting to.''

Ram is one of 10 Americans in the tournament - five seeded - and he's making a solid run.

''I've done this for long enough, it's a completely different match, a different day,'' Ram said of the short turnaround. ''A completely different opponent is really more of an issue. I had to play with a little bit of a different strategy, a little bit of a different outlook on it, but I played pretty well.''

In other action, fifth-seeded Adrian Mannarino of France beat Tommy Haas of Germany 6-7 (5), 7-6 (1), 6-4 in a match suspended by rain Tuesday.

Seventh-seeded Steve Johnson of the U.S. was ousted by Tatsuma Ito of Japan 6-4, 6-4; and Australia's John-Patrick Smith beat 18-year old American Jared Donaldson 6-3, 6-1.

Ram broke serve in the seventh game of the opening set to take control. He closed the set with a forehand winner.

With fans still entering the grounds next to the International Tennis Hall of Fame, Ram took charge, going up 3-1 in the second set.

''I guess I was executing pretty well,'' he said. ''It's a good thing if you can frustrate your opponent.''

Sugita lost the first three points on serve in the final game of the match before returning a backhand long, ending it in 67 minutes.

Ram edged Isner 10-8 in a third-set tiebreaker.

On Saturday, former world No. 1 and two-time major champion Amelie Mauresmo of France heads the 2015 class into the International Tennis Hall of Fame.