Stanislas Wawrinka has revealed that it was pleasing to produce the perfect response to a difficult challenge in his victory over Guillermo Garcia-Lopez at the Australian Open.

The defending champion continued his bid for back-to-back titles in Melbourne by progressing past Garcia-Lopez in four sets, and he admits that the Spaniard made it hard to get over the line.

"It was a really tough battle today. I was up two sets and a break but it was really tough to win the fourth, but overall, I am happy to get through," Wawrinka told reporters.

"It was a good level. I think the game lasted just over three hours but it's good to get one more win.

"It's always tough to play Guillermo. He plays with a lot of rhythm and puts a lot of pressure on from the baseline but I think that I served well today."

Wawrinka will meet David Ferrer or Kei Nishikori in the last eight.