Dimitri Payet marked his return at Marseille with defeat.
Payet's Ligue 1 return ended in despair for Marseille as struggling Metz produced a shock 1-0 win.
Metz substitute Yann Jouffre provided the decisive moment of a dull contest eight minutes from time when goalkeeper Yohann Pele failed to deal with his 20-yard free-kick.
Payet left West Ham in a £25million move last weekend and made his second Marseille debut as a substitute in a Coupe de France victory over Lyon on Wednesday.
The France international was again left on the bench until the 55th minute.