He could meet Nadal in the semi-finals.
Rafael Nadal's fine form continued with a straight-sets win over David Goffin to set up a Madrid Open semi-final with Novak Djokovic. I don't know how much, you know, I can play, how much this wrist going to hold for couple more matches.
"I do think the tournaments are going to do what they think is going to sell the most tickets, give them the most coverage, get the most people in to watch", Murray told BBC Sport.
"Novak is someone that I don't have good record (against)", Nishikori said.
"I'm still finding my way to that consistency level and quality of tennis that I'm looking for", Djokovic admitted. "If we both play well ... it can go either way". The third-seeded Halep, who lost the 2014 final to Maria Sharapova, will play Kristina Mladenovic of France. Sixth seed Tomas Berdych also did not have any problems while disposing of Robin Hasse of the Netherlands 7-6 (7-5), 6-3.
23-year-old Thiem broke the Croatian in the seventh game of the second set and then routinely held his serve to close out the match. The big serving power man from Canada had played little this year as he contended with a leg injury, and he was up against a man who is one of best movers on a tennis court: the slight and nimble Goffin makes up for lack of stature with speed and timing.
Nadal though did not have it all his own way and took almost three hours to put away enigmatic Italian Fabio Fognini 7-6 (7-3) 3-6 6-4 and he was left fuming by his sub-par performance.More news: Trump interviews 4 candidates to post of FBI director
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That set hung in the balance until Djokovic was able to claim what proved to be the decisive break in the 11th game of the set and he was then able to serve out to progress into third round.
Rafael Nadal's quest for a third straight title after wins in Monte Carlo and Barcelona faces a stiff test against Nick Kyrgios in the night session.
Djokovic found himself a break down in the third but fought back to set up a third-round clash with Feliciano Lopez, a 6-3 3-6 7-6 (7-3) victor against Gilles Simon. Cuevas won one of the points of the tournament with a no-look victor with his back to the court after a lob shot by Zverev early in the second set.
Fourth seed Nadal won 6-3 6-1 in 72 minutes in a match which showed promise early but quickly became a procession.
Predominantly playing the slice, Lopez hit the drop shot effectively at times to drag his opponent forward, but Djokovic drained errors or shot balls from the Spaniard's one-handed backhand as well.
On the other hand, Djokovic has not had the best of starts to the season as he is yet to reach the final of a tournament after his title-winning run at Doha.