A churning stomach left a nauseous John Isner looking depleted before a shot was struck. By the time Isner bruised successive aces off the back wall late in the match, Nicolas Almagro was wearing the queasy expression of a man who had been force-fed misery.

Playing with urgency on key points, Isner blasted 17 aces and did not drop serve in a 7-5, 6-3 victory that sent him into the Sony Open fourth round for the second time.

It was the first hard-court clash between the pair and from the opening coin toss Isner, who spent some of the day sick in bed according to TennisTV.com’s Robbie Koenig, wasn’t exactly exuding much positive energy. The 6’10” American operated with measured movements and stoic expression during the early stages. Broken twice in his second-round win over Donald Young, Isner was pushed to 30 in his first three service games tonight and when he netted a lethargic forehand to face double break point in the seventh game, the big man looked wobbled. But Isner erased the first break point with a flat inside-out forehand winner and benefited from a careless backhand error from Almagro to save the second, eventually holding for 4-3.

A beautiful ball striker, Almagro owns all the shots and backed up his  stinging serve he leans into with the full force of his body weight in issuing four love holds. Pressure can constrict the sometime temperamental Spaniard and Almagro looked spooked when he followed up an Isner an inside-forehand winner by netting a forehand to face double set point. Launching himself into a 134 M.P.H. serve winner he saved the first, but on the 13th shot of the next rally, Almagro’s backhand sailed long and Isner had a one-set lead after 35 minutes of play.

The 19th-ranked Almagro has tried to minimize the mood swings and cranky posture that has plagued him in the past, but it had to be demoralizing facing a guy who looked like he was running on fumes at the start only to grow stronger on serve as the match progressed. When you see Almagro launch a one-handed backhand swing volley winner as he did in the sixth game of the second set, you wonder how it’s possible a player so skilled can have a losing career record on hard court.  But the pressure of keeping pace with the massive server caught up with the former No. 9 who sent a nervous forehand into the middle of the net to face a third break point. Isner, who called for the trainer after holding for 3-2, ran around his backhand and zapped a diagonal forehand winner, breaking with a clenched fist for 4-2.

Almagro hit the ball well much of the night—he just didn't get to touch the ball much when Isner was serving in the second set: Long John won 20 of 25 points played on his serve in the second. Tormenting the Spaniard’s one-handed backhand with his hellacious kick serve on the ad side, Isner varied the direction, spin and speed of his serve masterfully (TennisTV.com stats showed his serve speed ranged from 89 to 138 M.P.H. on the night). He closed the 71-minute match with two aces and will face No. 7 seed Tomas Berdych for a quarterfinal spot.