Jose Mourinho has not ruled out making further additions to his Manchester United squad before the summer transfer window closes.

At his official unveiling at Old Trafford at the beginning of the summer, Mourinho outlined his plan to make four signings this summer to reinvigorate the side that finished outside of the Champions League places last season.

By that point, the club had already confirmed the arrivals of Eric Bailly and Zlatan Ibrahimovic. Henrikh Mkhitaryan followed shortly after and the £89m ($117m) arrival of Paul Pogba from Juventus seemingly brought an end to their incoming business.

The former Chelsea manager could still have one last surprise up his sleeve, however.

When asked about the possibility of more signings, he told a press conference: "The market is open until 31 August, but I am very happy with the players I have. I keep saying that I don't talk about players from other clubs."

Jose Mourinho
Manchester United might not be done yet in summer transfer window. Ben Hoskins/Getty Images

United are reportedly considering Southampton's Jose Fonte as a possible fifth summer recruit. ESPN understands Mourinho is keen to add the Portugal international, valued at £8m by the Saints, to his squad before the end of the summer transfer window on 31 August.

Fonte has admitted he is flattered by interest from United but with just two weeks of the summer transfer window remaining, Southampton are unlikely to consider selling their captain.

Saints take on United at Old Trafford on Friday night (19 August) and manager Claude Puel is unconcerned by the speculation.

"There is no problem with Jose," he told reporters, according to Southampton's YouTube channel. "This rumour is strange just before the game against United. There is a possibility he plays against United. He is a very good professional; he makes good training sessions this week. It is important to have Jose with us and I hope he will against United."