Rafael Nadal confirmed that he is once again suffering from a back problem but is unaware of how serious it is, the Spaniard revealed after reaching the fourth round on Saturday.

Nadal took his winning streak in Paris to 31 with a 6-2, 7-5, 6-2 victory over Argentina’s Leonardo Mayer in the third round.

The eight-time French Open champion was serving at an average speed of 156km/hr throughout the match and later admitted he is feeling pain in his back – the same kind of injury that troubled him during his Australian Open final against Stan Wawrinka.

“I felt some pain in my back, so that's why I slow down my serve a bit,” said Nadal, who turns 28 next week. “I felt a little bit from the beginning (of the match) and in the second match I was not serving that fast, too.”

Quizzed on whether the back was a concern, Nadal said: “I had the problem in Australia, but hopefully not.”

Nadal raced to a 5-1 lead en route to clinching the opening set which saw him break twice and drop just one point on his first serve.

The Mallorcan broke in the fourth game of the second set for a 3-1 lead but later allowed Mayer back in the set – the world No65 taking three games in a row to edge ahead 5-4.

Nadal broke again however to run away with a 60-minute second set. The pair exchanged breaks early in the third set but Nadal won the last five games of the match to book a place in the last 16 for a tenth straight year.

He now ties Roger Federer for the record of most consecutive appearances in the French Open fourth round. Further prompted by Spanish media, Nadal repeated what he had said earlier about his back.

“I don't usually lie. As I said, my back was hurting a little, and this is what I said on day one,” said Nadal. “I'd rather not talk about my back. I'll play as best as I can, I'll put up a good fight to try and win.

"My back is not that important. It's not that important, because I wouldn't really like to give you too many details. I am the way I am, and I'm happy to have reached this level. I won a three‑set match, which is important.”