Marseille have made Michy Batshuayi their second signing in two days as they seek to offset the potential departure of Mathieu Valbuena.
France playmaker Valbuena's agent claims his client is considering a move after the World Cup, with offers from around Europe.
Romain Alessandrini, who joined his hometown club from Rennes on Wednesday, will help fill the void in attacking midfield and new coach Marcelo Bielsa now also has a fresh striker to call upon in Batshuayi.
The 20-year-old scored 21 league goals for Standard Liege last season, placing him second in the Belgian Pro League scoring charts behind Lokeren's Hamdi Harbaoui.
Those performances also earned him the Ebony Shoe, awarded to the best player of African origin in the Belgian league, and persuaded Marseille to part with a fee which reportedly could rise to 6million euros (£4.8m).
The Belgium Under-21 international was part of national coach Marc Wilmots' provisional 30-man squad for the World Cup and though he did not make the final 23, he had been linked with the likes of Everton, Tottenham, Schalke, Benfica and Porto in recent months.
Valbuena is also likely to have his choice of destination should he choose to capitalise on his impressive displays in Brazil with a move.
Premier League clubs Arsenal and Liverpool, Serie A pair Fiorentina and Napoli and Valencia of the Primera Division have all been reported as tracking the diminutive 29-year-old.
Valbuena has spent eight seasons with OM, scoring 38 goals in 332 appearances. The club's most successful season in that time was 2009-10, when they won the Ligue 1 title and the first of three successive Coupes de la Ligue.
His agent Jean-Pierre Bernes told French radio station Europe 1: "He has a contract with Marseille and they are not a small club, they are a big club in France.
"But it is true that given his performances, and if there is the opportunity with a club, it is something we will examine and Marseille as well.
"Nothing is set, there is no destination fixed, there are contact with certain clubs in different European leagues."