!PicMIAMI—Today's matches will produce the first two semifinalists of the men’s draw, and fill out the semifinal brackets on the women's side, now that Maria Sharapova (seeded No. 2) and Caroline Wozniacki (No. 4) have advanced to that stage. Let’s take a quick look at all four singles matches on tap for today:

Agnieszka Radwanska (No. 5) vs. Venus Williams: This is the most intriguing match-up of the day and one that I’ll write about, even though Venus has dominated their head-to-head, 5-1. That’s because Radwanska has improved since their most recent match, a straight-sets blowout here in 2010. I’m curious to see if Venus can handle Radwanska’s ultra-defense. How you can you not pick the older Williams sister to win, seeing what she’s done here so far?

Janko Tipsarevic (No. 9) vs. Andy Murray (No. 4): Yesterday, Tipsarevic told me he was relieved to have a relatively quick win over Grigor Dimitrov, because today would be “very tough match.” True enough, but their head-to-head is 2-2 on hard courts (4-3 to Murray overall), so you know Tipsarevic is in with a shot. Ivan Lendl, Murray’s coach since the end of last year, is here in Miami and red as lobster (guys like Lendl don’t do sunblock!); I expect him to be blistering up by the time this one is over, but I like Murray to win.

Victoria Azarenka (No. 1) vs. Marion Bartoli (No. 7): After that remarkable comeback against Dominika Cibulkova, Azarenka will be feeling 10 feet tall and bulletproof, and—unlike Andy Roddick yesterday—she’s had a day of rest after that physically and emotionally draining win. Azarenka is 8-2 against the French “maid Marion” and has a hard-court win over her already this year (Sydney). I don’t see an upset here.

Rafael Nadal (No. 2) v. Jo-Wilfried Tsonga (No. 6): Although Nadal is ahead overall, 6-3, Tsonga has won two of their last three meetings, which have been on clay, grass, and hard courts (guess the surface on which Nadal won; first prize is a bull’s head logo!). The men are playing the second match at night, and if it’s anywhere near as windy tonight as it’s been for the last 12 or so hours, Tsonga has a good chance. It just doesn’t feel right to end this without predicting at least one upset, so let’s go with Tsonga.

-- Pete Bodo