Gignac travelled to England last week with media reports linking him to a move to Fulham but negotiations broke down and the striker was forced to return to Marseille, where he has struggled to make an impact after joining from Toulouse last season.
"I did not do all it takes to perform well last season," Gignac admitted in a press conference earlier this week.
"I'm back with extra motivation 10 times stronger after my pride was hurt. I am going to get off my bottom and show that I am the striker they [the Marseille officials] expect."
Marseille, the 2010 champions, have yet to win a league game this season, having drawn three and lost one in a lacklustre start.
Gignac, who scored only eight goals from 31 Ligue 1 matches last season, has been struggling with his fitness and coach Didier Deschamps went as far as sending him to a slimming course in Italy last month.
"It is not a sanction," Deschamps said at the time.
Gignac could start Saturday's game against fifth-placed Rennes as Ghana forward Andre Ayew is doubtful after suffering a possible groin injury in an African Nations Cup qualifier against Swaziland last week.
Elsewhere, Paris Saint-Germain will rely on new signing Javier Pastore to guide them against Stade Brest on Sunday as the big spenders look to stay close to leaders Montpellier, who host Nice also on Sunday.
Uruguay captain Diego Lugano, who joined in the final days of the transfer window, could make his debut at the Parc des Princes in central defence.
"I feel very well [physically] as I trained with [former club] Fenerbahce during the close season," Lugano, who played 70 minutes with his national team in a friendly against Ukraine last week, told the club's website.
Second-placed Olympique Lyon, who travel to promoted Dijon on Saturday, could leapfrog Montpellier into top spot, at least for a day, if they win.
Champions Lille could take new signing Joe Cole with them when they travel to Saint-Etienne on Saturday.
"I think he is a good signing, we can see that he is very skilful with the ball," said midfielder Mathieu Debuchy.
