The Metz striker has been in excellent form this season. He has posted 12 goals and three assists in 24 Ligue 1 starts.
A report from the Express claimed both Newcastle and Leicester were keen on the player ahead of the January transfer window.
But now it appears another Premier League club is pushing for his signature.
The same report cites Newcastle and Sevilla as others keen on the Senegal international.
Diallo, 24, has helped Metz to three wins in their past six games to move them three points clear of the relegation zone, posting two goals and two assists.
Chelsea may have looked at him as they wish to add more firepower to their squad. The Blues have relied on Tammy Abraham, but he has struggled with fitness of late.
Newcastle and Leicester, meanwhile, have scoured the French market before and managed to find some excellent buys.
The Foxes have added Fousseni Diabate, Rachid Ghezzal and Youri Tielemans in recent seasons while Newcastle signed Allan Saint-Maximin and Emil Krafth from France last summer.
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