Nadal, del Potro through to the quarterfinals at Rio 2016

Rafael Nadal is into the quarterfinals at the Olympics in his first tournament in over two months.

The 14-time major champion beat 15th-seeded Gilles Simon of France 7-6 (5), 6-3 in a match delayed a day by rain. He also plays doubles and mixed doubles later Thursday.

The 2008 gold medalist withdrew from the French Open because of an injured left wrist and has said he wouldn't be playing this week if it weren't the Olympics. Nadal was supposed to be Spain's flag bearer in 2012 but missed the London Games because of a bad knee.

He finally led out the delegation at last Friday's opening ceremony. In his toughest test of his three singles matches so far, Nadal had 28 unforced errors in the first set but just 12 in the second.

Juan Martin del Potro got an extra day of rest then a come-from-behind three-set win to also reach the quarterfinals of the Olympic tennis tournament.

The 2009 U.S. Open champ stunned top-ranked Novak Djokovic in the first round Sunday, part of nearly seven hours on court between singles and doubles in a span of about 25 hours. Then his third-round match Wednesday got rained out, and he looked strong in the final set in beating 117th-ranked Taro Daniel 6-7 (4), 6-1, 6-2 on Thursday in 2 hours, 12 minutes.

Dael Potro's ranking is actually worse than Daniel's - 141st in the world - as he's coming back from three left wrist surgeries. The Argentine isn't sure his conditioning can hold up long enough to win his second Olympic singles medal to go with his bronze from 2012.