Marseille announced the signing of 25-year-old Senegalese international Ismaila Sarr late Monday, further strengthening their front line following the arrival of Pierre-Emerick Aubameyang.
The winger is reported to have joined the French club on a five-year contract following a 13 million euro ($14.4 million) deal, although there was no official confirmation from Marseille.
Sarr is the second big-name signing to arrive at the Stade Velodrome in recent days after Aubameyang joined on a free transfer from Chelsea last week.
The arrival of two forwards casts further doubt on the future of Alexis Sanchez. Out of contract since the end of June, the Chilean attacker has not yet committed to extending his stay on the south coast.
The move signals a return to French football for Sarr who began his career in 2016 at Metz, before joining Rennes in 2017.
The winger scored 18 goals and made 16 assists in 77 appearances for the Breton club.
This was enough to attract the Hornets' attention in 2019. Sarr scored 34 goals and made 24 assists in 131 appearances during his four years in England.
Sarr, who was Watford's record signing, won the Player of the Season award for 2020-2021 season after his 13 goals helped lead the club back to the top flight of English football.
"Thank you and good luck, Isma", Watford wrote on Twitter, which is being rebranded as 'X'.
Last year, Ismaila Sarr met with success on the international stage when he won the Africa Cup of Nations with Senegal. The winger boasts 54 caps for the Lions of Teranga.
It has been a busy summer transfer window so far for Marseille. In addition to Aubameyang, Sarr joins defender Renan Lodi and central midfielder Geoffrey Kondogbia, both signed from Atletico Madrid.