After a week of surprising results that included the early elimination of world no. 1 Novak Djokovic, the semifinals of the Rio Olympics men’s singles will feature three players in the world top 10 and a former U. S. Open champion who is climbing back.

In the first semifinal, two-seeded Andy Murray will face fourth seed Kei Nishikori in a rematch of a classic Davis Cup five-setter in March.  In that match, the Japan native fought back from a two-set deficit only to fall short in the clay court battle.  Murray holds a 6-1 career head-to-head advantage.

Nishikori will attempt to use his quickness edge against the reigning gold medalist and two-time Wimbledon champion who has recently excelled in all aspects of his game.  A quick start by Nishikori in the best-of-three could pressure the Brit who can, at times, slip into a funk with negative emotions.  Meanwhile, possessing one of the best returns of serve in the game, Murray will look to attack the Nishikori second serve which can be suspect.  It will be vital for the 26-year old to place a high percentage of first serves in play.

However, Nishikori has a solid return of serve as well, and can mix in some effective net play to pressure Murray.  Both players were pushed in three-set battles during their respective quarterfinal matches and the ability to maintain high energy levels after playing multiple events during the week, could potentially be a factor.

But it will take a strong effort by Nishikori to advance past Murray, who has not lost since the Roland Garros final.  He has won 16 straight matches and 27 of his last 28.  During this streak, the world no. 2 has won titles at Wimbledon, the Aegon Championships in London, and the Rome Masters.

The second semifinal features two players who entered Rio with questionable health concerns. Each had an uncertain status as to whether they could compete at a level that would allow for a deep run at the tournament.  But Juan Martin Del Potro and Rafael Nadal have certainly answered any question by virtue of their level of play during the week, despite cautioning that they are not 100 percent.

Del Potro played one of his strongest matches in some time when he eliminated Djokovic in the first round.  And he has built upon that result, maintaining his high level of play through the quarterfinals.  His forehand has been a massive weapon during his run and his backhand, which had been hampered due to injury, has been solid enough.

Meanwhile, Nadal has shown no signs of a wrist injury that forced him out of Roland Garros, his last tournament played prior to the Olympics.  Nadal has only dropped one set during the week but has logged a large amount of time on the court, which includes a run to the gold medal in doubles.  Nadal’s stamina following a heavy schedule of tennis will be something to assess during Saturday’s match.

The two have met 12 times, with Nadal taking 8 of those matches, but have not played since 2013 when Del Potro won their last meeting at the Shanghai Masters.  However, on hard courts, they have an even 4-4 record head-to-head.

Nadal was surprised to have advanced to a medal game, “Being at the semi-finals is something that a few days ago I wouldn’t even imagine,” he said.

Meanwhile, Del Potro had a similar sentiment, “I don’t even know how things are going so well because I didn’t do any preparation for the tournament.”