World No. 3 Rafael Nadal will take on Frenchman Gael Monfils in the fourth round of the US Open tonight.

Nadal looked in good form in his last match against fellow Spaniard Nicolas Almagro, but he appeared to tear or strain his stomach muscle—an obvious concern ahead of his match with Monfils.

The duo has already played each other twice this year—Monfils won their encounter in Doha, while Nadal got his revenge in Rotterdam.

Nadal reached the semifinals of the US Open in 2008 before losing out to Britain's Andy Murray.

The Spaniard took the tennis world by storm earlier in 2009, when he won the Australian Open for the first time in his career.

Should Nadal triumph in New York on Sunday, he will complete the career Grand Slam.

Roger Federer did this earlier in the year when he won the French Open.

If Nadal can play to his potential over the next few days, then he has every chance of upsetting the Betting Odds and winning the US Open title for the first time in his career.