Our guide to what to look out for on Day 7 of the London 2012 Olympic tennis event...
Roger Federer (SUI)  v Juan Martin del Potro (ARG) : Federer stands just two wins from that elusive singles gold medal. The reality is that’s still a long way from glory. While Rafael Nadal's no-show left a gaping hole in the men’s draw, few were surprised when the Argentine – the last man outside the Big Three to have won a major – filled that semi-final position. Del Potro has only beaten Federer twice in 14 meetings but the match everyone still talks about is that US Open final he clinched. Last time they played Delpo let a two-set lead in this year’s French Open quarters slip.
Pick: Grass leans to Federer in three sets.
Victoria Azarenka (BLR)  v Serena Williams (USA) : It’s the Wimbledon semi-final all over again. Williams won that one in straight sets before going on to lift the Venus Rosewater Dish for a fifth time. In the Olympic arena Williams is hungrier given she’s now a member of the over-30s club so has less time on her side than the shrieking Belarusian. She was ruthless against Wozniacki but will have a much tougher time of it against the top seed who has rebounded from her first-round wobble in style.
Pick: Azarenka will come out firing but Williams in three.
Novak Djokovic (SRB)  v Andy Murray (GBR) : Having enjoyed a relatively comfortable path to the semis – he hasn’t played anyone yet ranked in the top 10 – Murray will have to step it up a gear today if he is to spring the upset on the Serb. Djokovic has endured the toughest path of the four semi-finalists – beating Tsonga, Hewitt and Roddick in his last three matches but will be keen to surpass his bronze-medal showing from Beijing four years ago. Expect raucous support for the Brit to play a part.
Pick: Muzz to send the home crowd wild with a marathon three-set win.
Maria Sharapova (RUS)  v Maria Kirilenko (RUS) : It’s the all-Russian all-Maria semi-final no one predicted. The one-time doubles partners and glamour girls of Russian tennis are both 25 and fairly evenly matched in their head-to-head, 3-2 in Maria S’s favour. Maria K did pull the upset in Round 1 of the Australian Open though back in 2010 and their last meeting at Indian Wells this year went to three. They’ve never met on grass though, which will favour Maria S’s heavier ground-strokes. Maria S has looked fiercely determined at these Olympics, her straight sets dismissal of Clijsters yesterday putting her in the driver’s seat to win through to the gold medal play-off.
Pick: Maria S in two.
Others to watch:
Laura Robson/Andy Murray (GBR) v Samantha Stosur/Lleyton Hewitt (AUS): A classic Great Britain versus Australia battle, the Ashes Test match decider of the Olympic tennis, if you like.
Maria Kirilenko/Nadia Petrova (RUS)  v Serena Williams/Venus Williams: Maria and Serena have singles semi-final duties to complete before this one. Interesting to see what bearing those results have.
Bob Bryan/Mike Bryan (USA)  v Julien Benneteau/Richard Gasquet (FRA): Surely the American twins can almost touch an elusive gold medal now, not to jump too far ahead just yet.
Lisa Raymond/Liezel Huber (USA)  v Andrea Hlavackova/Lucie Hradecka (CZE) : Did someone say all-USA women’s doubles final?
David Ferrer/Feliciano Lopez (ESP) v Michael Llodra/Jo-Wilfried Tsonga (FRA) : European rivals and four Davis Cup stalwarts all on the same court.