Nadal wins again, yet to be tested

So, the big question: Is Rafael Nadal firing on all cylinders in his quest for a 10th French Open title?

Short answer: It is still too early to tell, because through the first three rounds, he has yet to be seriously tested.

Andrey Kuznetsov certainly wasn't a reliable gauge of the 14-time Grand Slam champion's form in a clay-court season when his ranking has slipped to seventh - the Spaniard's lowest spot in a decade - and which Nadal himself acknowledges has been ''up and down.''

Kuznetsov, ranked 120th, folded 6-1, 6-3, 6-2 in their third-round match Saturday.

''Being in the fourth round is great news for me,'' Nadal said after stretching his Roland Garros winning streak to 38 matches.

He has yet to drop a set in his 11th French Open campaign. That should leave him fresh for the second week. The 28-year-old, who turns 29 on Wednesday, will need the energy.

Next up is a first-ever meeting for Nadal with 22-year-old Jack Sock, the last U.S. man in the draw.