The transfer window may officially shut at 5pm on Thursday but Blackpool and Fleetwood can still be active in the transfer market thanks to an EFL rule.
On the eve of the new season, which starts with United's clash against Leicester, Mourinho also claimed that finishing second last season, 19 points behind champions Manchester City, was "one of the greatest achievements" of his career.
Liverpool FC finished in fourth spot last term but there is an air of positivity around the Anfield club after they brought in four new players in the transfer window.
United have been linked with several other signings, especially at centre-half , but Mourinho doubts deals will be done, telling reporters: "I'm not confident and the market closes today".
This summer has already seen some mega-deals take place regarding Premier League clubs with Riyad Mahrez moving from Leicester City to Manchester City for a huge £67m, whilst Naby Keita joined Liverpool for £62m in a deal that was agreed on last summer.
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'It is hard for me to understand we finish second which I keep saying, that I won eight championships and three Premier Leagues but I keep feeling the second last season was one of my biggest achievements in the game'.
Israeli strike kills at least two Palestinians at Hamas site in Gaza
The incident took place as Egypt was working to broker a cease-fire deal between Hamas and Israel. It then cuts to footage of a shell hitting the post and an explosion.
'Its hard for me to believe we finished second.
"You also have to consider that Liverpool are City's Kryptonite".
"They returned on Monday, trained Monday, Tuesday, Wednesday and today so you can imagine they are not really fit and ready but we have needs", Mourinho said.
See which players and managers have come and gone.
Marcus Rashford, Victor Lindelof and Romelu Lukaku returned early and should be available.
"I told that during pre-season it looked like I was saying something absolutely out of order, something insane, I repeat and maybe tomorrow the reaction is the same: Pre-season hard when you don't have your players to work, that's as simple as that".