Jelena Ostapenko suffered her second successive first-round loss at the French Open since winning the 2017 title as she was beaten by former world number one Victoria Azarenka on Tuesday.
Considering the calibre of her opponent, a 6-4, 7-6(4) loss was not as demoralising as last year's defeat by Ukraine's Kateryna Kozlova.
But it continued a steep decline for the 21-year-old who also fell in round one at the Australian Open and has managed back-to-back wins just once in 2019.
The match statistics made grim reading for Ostapenko with 60 unforced errors to Azarenka's 19.
While the Latvian continues to struggle, Azarenka is heading in the right direction having risen back into the top 50 for the first time since giving birth to son Leo in December 2016.
Yet it was the Belarussian who began the match in charitable fashion, opening with two double faults before watching two Ostapenko backhands flash by her.
She broke back in the next game but dropped serve for the third time in the set to trail 4-3.
Ostapenko double-faulted four times in the next game to hand back the advantage, then twice more at 5-6 to surrender a scrappy first set.
She continued to mix flashing winners with unforced errors in the second, leading 4-2 but allowing Azarenka back in.
Ostapenko served for the set at 6-5 and led 30-0 only to offer up more free points to her grateful opponent.
In the tiebreak Azarenka brought up match point with a thumping forehand winner and Ostpenko's 60th unforced error ended the contest.
Minor hiccup as defending champion Halep advances
Simona Halep overcame a second-set blip as she kicked off her French Open title defence with a 6-2, 3-6, 6-1 win over Australian Ajla Tomljanovic to reach the second round.
The Romanian third seed played some neat and tidy tennis in the opening set, lost the plot in the second and then wrapped up the victory to set up a meeting with Magda Linette of Poland.
Halep seized control with an early break and tightened her grip in a one-sided first set, containing her opponent's power.
But Tomljanovic started to hit the ball harder and by the time Halep had started to figure out how to deal with her pace the Australian had taken the second set.
Experience, however, prevailed in the decider as Halep won six of the seven remaining games.
Osaka survives huge first-round scare
World number one and top seed Naomi Osaka flirted with an opening-round exit at the French Open but recovered from a first-set horror show to beat Anna Karolina Schmiedlova 0-6, 7-6(4), 6-1.
The 21-year-old Japanese player, aiming for a third successive Grand Slam title, was allowed only nine points in the first set against the world number 90 from Slovakia.
She then let a 3-0 lead slip in the second set before twice having to break her opponent's serve to stay in the match.
Once she won the tiebreak, however, her game clicked back into gear and she breezed through the decider.
She will be allowed no such lapses in the second round, however, when she faces former world number one Azarenka.
Karlovic, 40, beats Lopez in 'oldest' match
Croatia's Ivo Karlovic became the first man in his 40s to compete in a Grand Slam singles match for 27 years when he beat fellow-veteran Feliciano Lopez at Roland Garros on Tuesday.
Karlovic, who turned 40 in February, won 7-6(4), 7-5, 6-7(7), 7-5 against the 37-year-old Spaniard in the oldest French Open men's match-up in terms of combined ages in the professional era.
The last player to contest a Grand Slam singles match having turned 40 was American Jimmy Connors at the US Open in 1992.
Karlovic, well used to setting records for longevity everywhere he travels, is also the oldest man to compete at the French Open since 41-year-old Istvan Gulyas in 1973.
It was a typical Karlovic match with the 2.11 metre tall Croat dominating his service games.
He took the opening set on a tiebreak but did not engineer a break point on the Lopez serve until pouncing with his opponent 5-6 down in the second set.
Almost inevitably the third set went to a tiebreak and when Lopez missed a routine volley at 5-5 it handed Karlovic a match point, only for him to be denied by a lucky backhand return that left him flat-footed at the net.
A fifth set loomed when Lopez led 5-2 in the fourth set but Karlovic rattled off five straight games to move through.
Juan Martin del Potro fired up his power game after a sluggish start to ease past Nicolas Jarry in an all-South American first round clash at the French Open on Tuesday.
The eighth seed, a semi-finalist last year, won 3-6, 6-2, 6-1, 6-4, the four sets taking a little more than four hours.
"The conditions were difficult at the start with wind and some rain, and Nicolas played so strong, but after that I took control of the game and played better," Argentine del Potro said on Court Suzanne Lenglen.
Chilean Jarry, ranked 58th and a finalist in Geneva last week, was a potentially tough hurdle for Del Potro, who is in just his third tournament since yet another injury break, this time to his right knee.
In the opening set Chilean Jarry took advantage of a couple of gifts to break Del Potro's opening service game and remained solid to pocket the opening set.
The 30-year-old Del Potro is not one to panic, however, and when three wayward forehands and then a Jarry double-fault handed Del Potro his first service break in the second game of the second set, the momentum quickly shifted.
It was one-way traffic after that as del Potro took charge to set up a second round clash with Japan's Yoshihito Nishioka, who beat American Mackenzie McDonald in five sets.
"I'm just happy to be playing tennis again and to be in Paris after all my injuries," said Del Potro who has missed a combined three years since 2010, mainly with wrist injuries. "I have great memories here.
"This tournament means a lot to the Argentine players and the fans. I'm excited to keep winning."
Del Potro was joined in the second round by compatriot Federico Delbonis, who beat Spain's Guillermo Garcia-Lopez.
Zverev digs deep to reach Round 2
Alexander Zverev was made to work hard to reach the second round of the French Open with a 7-6 (7-4), 6-3, 2-6, 6-7 (5-7), 6-3 win over Australian John Millman.
The German fifth seed, looking for a major breakthrough on the Grand Slam stage, needed more than four hours to see off the world number 56 and set up a meeting with Swedish qualifier Mikael Ymer.
The 22-year-old Zverev, one of the leading figures of the sport's 'new generation', claimed his best result at a major when he reached the quarter-finals at Roland Garros last year.
For a moment, it seemed he could be sent packing on his first day on court.
Millman cancelled out Zverev's early break with the German winning the resulting tiebreak in the opener before sailing through the second set.
But Zverev never looked comfortable in changing conditions on Court Philippe Chatrier and he was overpowered in the third, Millman taking the tie into a fourth set with a powerful forehand winner.
Zverev stole his serve but Millman turned it around to force a tiebreak, which he won to take the match into a decider.
That did not please Zverev, who destroyed his racket in frustration.
But a timely break in the ninth game of the fifth set had him serve for the match. There were no nerves on display as Zverev ended the contest on his first match point.
