Roddick advanced also today after receiving a walkover when Andy Murray of Britain withdrew with a right thumb injury from a fall in his previous round.

Karlovic at 6 feet, 10 inches tall is the tallest player ever to play in an ATP Tour event and is the best server on the tour.

Today Karlovic slammed 35 aces against Nadal and faced only two break points against his serve, both of which Nadal failed to convert.

Nadal never faced a breakpoint on his own serve in the two hour, 24 minute match.

“This was a very important win because I beat a specialist on this surface,” Nadal said, “When I touched the ball, I returned well. Matches like this are decided in two balls. It’s very tough mentally.”

Nadal reached the Wimbledon final the last two years, losing each time to world number one Roger Federer of Switzerland.

Karlovic's best Wimbledon finish was a fourth round effort in 2004. One of Karlovic's best wins was at Wimbledon in 2003 when he beat defending champion Lleyton Hewitt of Australia in his first match ever in at a grand slam tournament.

Karlovic recorded his fastest serve ever at 153 miles per hour last year at Nottingham. But he still trails the world's fastest server Roddick who has served at 155mph.