Rafael Nadal was pleased to beat Mischa Zverev at the Mexican Open in his first match since the Australian Open in January.
The top seed eased to a 6-3 6-3 victory and has now won 15 of his 16 matches at the tournament.
The Spaniard said afterwards: "I'm happy for the victory. It's never easy against Mischa, especially without competing for a while. I'll try to enjoy this moment for the next few hours and then be ready for tomorrow."
Nadal will play Nick Kyrgios in the second round after the Australian defeated Andreas Seppi of Italy 6-3 7-5.
"This tournament is hard and there's a lot of great players, so these kinds of matches can happen in the early stages," added Nadal. "Nick is one of the most talented players on tour. It's a big challenge for me and I hope to be ready for it."
Second seed Alexander Zverev saw off Alexei Popyrin 6-3 6-3 and will play David Ferrer next after the Spaniard edged to a 7-6 7-6 victory against Tennys Sandgren.
"I feel very happy. It was very emotional for me," said Ferrer who is taking part in the tournament for the final time.
"The crowd helped me a lot because I know these are going to be my last matches here, so I'm just trying to do my best on every point."
Third seed John Isner beat Adrian Mannarino 6-3 4-6 6-3 to set up an all-American clash against Sam Querrey who recorded a 6-3 6-2 win against Guillermo Garcia-Lopez.
Nadal is 2/9 to beat Kyrgios and 1000/1 to win the tournament outright.
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