Aryna Sabalenka began her eighth Roland Garros campaign with a commanding 6-1, 6-0 win over Russia's Kamilla Rakhimova.

With three-time reigning champion Iga Swiatek struggling for form, the 27-year-old Sabalenka tops the list of title contenders as she targets a fourth Grand Slam.

But the top seed confessed she is trying to get her head around the fact the French Open is the last of the four majors to still have line judges, with Wimbledon to adopt electronic line calling from this year.

The technology is now used at all men's tour-level events, but the same policy does not yet apply to the women's circuit.

It is a particularly contentious issue on clay, where the ball leaves a mark in the surface that can be used to determine where a shot hit the ground.

"Honestly, I'm so confused, I don't know (which I prefer)," said Sabalenka, who was involved in a strange incident last month in Stuttgart, where the electronic line calling system was not installed.

"I had situation with the referee in Stuttgart, and also there was tricky calls with the Hawk-Eye system in Rome. So I'm really confused what I prefer, to be honest."

Sabalenka received a warning for unsportsmanlike conduct for taking a photograph of a disputed ball mark in Stuttgart before exchanging a tense handshake with the chair umpire after the match.

"I guess there is some, like, old school why having the referees and calling the referee to check the mark," Sabalenka said on Sunday.

"I think that's something which brings like in old days, which is cool, probably. So I don't know. Honestly, I'm really confused with my opinion."

Sabalenka broke Rakhimova five times as she wrapped up victory in an hour to make a convincing start to her Roland Garros title bid.

The three-time Grand Slam champion will play Switzerland's Jil Teichmann or Italian qualifier Lucrezia Stefanini for a spot in the last 32.