Manchester United expected Romelu Lukaku to return to training on Tuesday.
Instead the Belgian remained in his homeland, seemingly in an attempt to force through his exit from Old Trafford.
United had granted Lukaku permission to train with former club Anderlecht up until Monday.
Sky Sports says the 26-year-old was expected to train at Carrington on Tuesday but was nowhere to be seen.
Italian clubs Inter Milan and Juventus have both been unsuccessful in attempts to sign Lukaku this summer.
United want at least £79m for the former Everton man.