I know theres no such thing as a lock... but the way these 3 have been playing, and their opponents I dont see how this loses. All in to return 36% profit in 21 total hours. Not so bad.
6/5/2013 5:00 AM ATP Tennis 127 Rafael Nadal* -1400 vs Stanislas Wawrinka
6/4/2013 8:00 AM WTA Tennis 301 Serena Williams* -1800 vs Svetlana Kuznetsova
6/5/2013 5:00 AM WTA Tennis 362 Maria Sharapova* -490 vs Jelena Jankovic
Highly unlikely as you say, but Sveta has given Serena some problems before - but was too frail mentality to complete most of them. Crafty vet. A good tournament for her recently.
Probably gonna win but those are some good opponents. 1 of the 3 could pull off the upset. I wouldnt make this bets constantly because only 1 of the 3 have to pull off the upset just 1 out of every 3 parlay bets. Not much value there. But to do it occasionally when you have a strong feeling should be alright. Good luck