Takumi Minamino was left ruing missed chances after making his Ligue 1 debut for Monaco in a 4-1 loss to Lens on Saturday.
The Samurai Blue attacker could not capitalize on either of two good first-half opportunities and largely struggled to make an impact from the left of midfield in manager Philippe Clement's 4-4-2 formation.
Minamino received a cross in scoring position in the fourth minute but did not get a shot away after controlling the ball on his chest.
With Monaco trailing 1-0, he made a close-range attempt from a scramble in the area but was blocked by Lens keeper Brice Samba.
"If I could have scored there, the result would have been different," said Minamino, who moved from Liverpool this summer in search of more playing time ahead of the World Cup.
The 27-year-old was benched in the 56th minute.
Lens moved to the top of the table with Monaco seventh after three rounds of the French top-flight season.
Elsewhere in Europe, former Japan forward Shinji Okazaki made his debut appearance for Sint-Truiden, who registered their first win of the Belgian top-flight campaign, beating Oostende 1-0 away on Toni Leistner's 17th-minute goal.
The 36-year-old Okazaki played the full game after starting up front in a Sint-Truiden XI also featuring countrymen Shinji Kagawa, Daiki Hashioka and Daniel Schmidt.
"I thought it would be good if I could play at full throttle to improve my feel for the game (and) I was able to do that for 90 minutes," said Okazaki, who was happy to reconnect with former World Cup teammate Kagawa.
"It's easy to know where to move whenever Shinji has the ball. I hope to score a lot of goals and contribute to the team winning."
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