MIAMI, (Reuters) – World number two Roger Federer  defeated American Andy Roddick 6-3 4-6 6-4 in front of a noisy  night-time crowd at Key Biscayne on Wednesday to set up a  semi-final with Serbian Novak Djokovic at the Sony Ericsson  Open.

Third seed Djokovic produced sparkling tennis to beat  Frenchman Jo-Wilfried Tsonga 6-3 6-4 but will now have a major  test in his bid to reach the final.

Roddick, cheered on by a partisan crowd, struggled against  Federer’s first serve in the first set and was broken twice.  The second set was a different story, though, after Federer  double-faulted on break point for a 4-3 lead.

The American served for the set at 5-4 and Federer had a  chance to break but in the end a long return on a serve secured  Roddick a third set.

In a tight deciding set, dominated by serve with the first  four games won to love, a stroke of luck set up Federer for the  match point.

Roddick, who had Miami Dolphins linebacker Joey Porter  screaming encouragement from the stands, was a one point away  from squaring the match at 5-5 but Federer’s backhand pass  attempt clipped the net and looped over the forlorn American.

A smart backhand pass then gave Federer a 17th win in 19  meetings with Roddick.

“I should have had it under control in the second set,”  said Federer. “I lost that and was under quite a bit of  pressure in the third set. So I’m happy I got through it.

“I got maybe a touch lucky at that deuce passing shot.  But, I mean, I hit it well and came up with a great shot and  match point,” he added.

The 13-time Grand Slam winner will have to be on top of his  game again today as his opponent Djokovic is showing signs  of a real return to top form.

Delivering dashing groundstrokes and generating plenty of  spin on his second serves, the Serb was on top throughout.

Tsonga had a chance to extend the second set but failed to  convert two break points at 5-4 and in the end Djokovic wrapped  up victory with an emphatic smash which brought roars from  noisy Serbian supporters.

Djokovic said there was no mystery ahead of him in  Friday’s semi-final.

“With Roger, there’s not much to say about him. He’s so  consistent in the major events. He’s been so dominant the last  couple of years. It is going to be a tough, tough encounter”.