Rock Creek Park was the site of John Isner's breakout tournament when he stormed to the 2007 Washington, D.C. final as a 416th-ranked wild card. Isner turned the same venue into a launching pad today.

The 6'10" American slammed 18 aces, did not face a break point, and won 18 consecutive points on serve to close out a 6-7 (5), 6-4, 6-4 victory over 2010 finalist Marcos Baghdatis.

Terminating points in quick bursts, Isner opened with two love holds, but failed to convert a triple break-point opportunity in Baghdatis' first service game. The bearded Cypriot belted a forehand cross-court to save the first, evaded the second when Isner's inside-out forehand sailed wide, and erased the third burrowing a serve into the big man's body. Neither man managed another break point as the first set escalated into the expected tiebreaker.

An imposing Isner had won 16 of his last 17 tiebreakers for an ATP-best 28-7 record in the sessions, but Baghdatis didn't blink, slamming his seventh ace down the middle for a 4-3 lead. Isner was up 5-4 when he hammered some punishing forehands that pushed Baghdatis a few feet from the back wall to defend. Eyeing the expanse of open court, Isner cut under the ball on a forehand dropshot bid that failed to clear the net. Baghdatis cracked a sliding serve down the middle for set point, then sprang into a return that repelled Isner backward, drawing a wayward forehand. He then unleashed a Rafa-style upper-cut and an extended "Come on!"

A streaky server, Bagdhatis likes to bang the flatter first serve down the middle on both sides, and he used it well to take the first set despite serving 42 percent. Baghdatis played a loose game at 3-all in the second, netting a routine rally forehand before dropping serve scattering a double fault wide.

It's one of the scarier sights in tennis: When the giant Isner's right arm whips up and out over the court, the returner has to commit almost on contact to have any shot of making contact. Just touching the blurring ball can look as challenging catching a cookie tossed from atop the Washington Monument. A kicker short in the box set up a forehand winner for set point; Isner blistered an ace off the line to level the match.

The 2006 Australian Open finalist can still generate the shotmaking flash when he's tuned into the muse, but Baghdatis' flat forehand and second serve can both go kablooey under pressure, and Isner tried pressuring the forehand on the big points.

Fighting off a break point in the opening game of the decider, Baghdatis stayed in step until a nervous stumble in the seventh game. He spit out successive double faults then watched Isner blast a forehand return down the line for triple break point. Sending a backhand return right back into Baghdatis' rib cage, Isner drew an errant backhand to break at love for 4-3. He extended his run to 12 consecutive points in backing up the break for 5-3.

Serving for the semifinals, Isner slammed three consecutive aces, including his fastest of the match—a 142 M.P.H. ace for 40-0—closing on a run of 18 straight service points. Isner will face 61st-ranked Dmitry Tursunov, who held off Marinko Matosevic in a third-set tie breaker, for a spot in the final.