Tennis: What to watch at Wimbledon

Serena Williams is currently on track to win all four grand slams in a calendar year. Photo / AP

The question of who will win Wimbledon is almost answered, with the women's semifinals overnight (NZT) and the men's semifinals 24 hours later.

What to watch for:

1. The 20th meeting of old rivals Serena Williams and Maria Sharapova.

If Williams can take out Sharapova tonight she will remain on track to winning her first true Grand Slam - winning all four major tennis tournaments in a calendar year - the first since Steffi Graf in 1988.

Williams is the top seeded player for women's singles and the favourite to win tonight's match. Of the last 16 matches the two have played, Sharapova has won precisely zero.

Thirteen of the 16 matches were won by Williams in straight sets. If Sharapova defeats the American great it will be a true victory for the underdog.

2. Former Wimbledon champ Andy Murray playing all-time great Roger Federer.

Home favourite Murray is determined to take out another win on home soil. If he knocks the second-seed Swiss out at this point it will foil the likely last chance the seven-time Wimbledon winner has to make an even eight.

Federer has never lost in the Wimbledon semifinals, holding a career 9-0 record. He has a 12-11 career edge over Murray, but the Briton beat him on Centre Court in the final of the 2012 Olympic tournament.

3. Defending champion Novak Djokovic going head to head with Richard Gasquet.

Gasquet, the lowest seeded men's singles player left in the tournament, unexpectedly knocked out French Open champion Stan Wawrinka in a marathon fifth set Wednesday, preventing Wimbledon from having the top four men's seeded players in the semifinals for the first time in 20 years.

Gasquet conceded that Djokovic was "of course" the favourite to win the match but his stamina against Wawrinka is a good sign he'll put up a hell of a fight.