World number two Rafael Nadal revealed a change in tactics was the key to him surviving a second round scare against Ernests Gulbis.

Nadal dropped the first set before battling back to eventually triumph 5-7, 6-2, 7-6, 6-3 over the Latvian teenager.

And the Spaniard admitted he had to shake things up.

Nadal said: "I had to change after the first set.

"In the beginning I tried to play aggressively, aggressive with the second serve, going inside, but it was impossible.

"He was serving too good.

"But later on I went more behind and I felt like I had a bit more control of the situation.

"I know I had a very tough opponent today and I'm very happy with the win."