ARYNA SABALENKA — REUTERS

PARIS — Aryna Sabalenka said she would continue to sign the bald head of her fitness trainer with a marker pen before matches as the bizarre ritual she began on a whim before her successful Australian Open defense continued to bring luck at the French Open on Saturday.

Ms. Sabalenka marched into the fourth of Roland Garros with a 7-5, 6-1 win over Paula Badosa and is now unbeaten in 10 matches at the majors, with television cameras invariably focusing on the shiny head of Jason Stacy each time, looking for her signature.

“It started from the beginning of the Australian Open. We all stand around. Me and Jason in the middle and I sign his head with, I don’t know, classical music playing in the back. Oh no, no,” Ms. Sabalenka said, struggling to hold back laughter.

“I don’t know. It somehow started as — I don’t want to swear right now because I’m trying to be better with my words — but we like to do weird stuff. And then I won the tournament and I was like, ‘Jason we got to keep tradition going.’”

“I wanted to do it in every tournament, every match, but he was just like ‘okay, let’s just at least pick this tradition for the Grand Slams’ and so far we are doing it.” — Reuters