Past battles will mean nothing for Novak Djokovic

The world number three beat his Czech opponent in straight sets in each of their two previous meetings but he had the utmost respect for Berdych even before he sent Roger Federer packing in yesterday's quarter-finals.

Djokovic, the 2008 Australian Open champion who is the only semi-finalist without a grass-court title, knows Berdych has improved out of all recognition since their last clash in Miami 16 months ago.

Tomorrow's tussle will be their first grand slam clash and their first meeting on grass, the surface on which Berdych has looked increasingly comfortable, with the prize a place in the final against Rafael Nadal or Andy Murray.

"I think he has improved a lot from the baseline," said Djokovic. "He always had the powerful strokes and shots but he was making a lot of unforced errors before.

"Now he's cutting that to the minimum, he's becoming more patient.

"He's a big server and he has powerful groundstrokes. Obviously, his weapon is his forehand. He also plays a lot of flat shots.

"Of course, physically he's very strong, very compact, and, of course, his serve is always there. So, if he serves well, he can be very dangerous."

The 6ft 5in Berdych, who is aiming to reach his first grand-slam final, demonstrated all those qualities and more in his shock victory over Federer.

He will also draw on the confidence gained from reaching the semi-finals of the recent French Open, where Murray was among his major scalps.

"Playing a grand slam semi-final is going to be very different to when we first played many years ago," said 24-year-old Berdych, who is hoping to become the first Czech man to play in a Wimbledon final since Ivan Lendl in 1987.

"It's going to be similar to the match I played against Murray at Roland Garros.

"It will be like we're meeting for the first time. I think it's going be a really, really tough one. I think we have both changed a lot.

"Of course you need to have some confidence to get to the semi-final so I think it's going to be really the same for both of us. I'm looking forward to the match."

Djokovic came into Wimbledon as a dark horse after a run of indifferent results but, in seeing off Lleyton Hewitt on his way to the last four, has gradually begun to recapture the form that took him to victory in Melbourne two and a half years ago.

He was especially delighted with his performance against shock quarter-finalist Yen-Hsun Lu yesterday and is not lacking in confidence as he prepares for his second Wimbledon semi-final.

"If I perform as well as I did in my last match, I think I have a good chance," said the 23-year-old from Belgrade, who was forced to retire from his semi-final with Nadal three years ago with a foot injury.

"I was struggling with the level of my performance throughout the last five or six months, there were a lot of ups and downs.

"But right now I'm playing great. It definitely makes me happy."