Jose Mourinho is well on his way towards building a side capable of challenging for the Premier League next season.Last summer, the Portuguese manager signed Eric Bailly, Paul Pogba and Henrikh Mkhitaryan for a grand total of approximately £145 million.The trio all impressed in bursts throughout the 2016/17 season - especially Bailly - and are expected to continue improving at Old Trafford.As for this summer, Mourinho has completed moves for Victor Lindelof (£30.75 million from Benfica) and Romelu Lukaku from Everton for £75 million.Further signings are expected, with Nemanja Matic, Fabinho and Tiemoue Bakayoko all linked with big-money transfers.One thing Mourinho doesn't need more of in his Manchester United side is height; David de Gea, Marouane Fellaini, Pogba, Timothy Fosu-Mensah, Lukaku, Bailly and Lindelof are all at least 6'2" tall.United have never been a long-ball side, but that style of play could always come in handy if they're in desperate need for a goal.It's in pre-season training where Mourinho will look to further implement his philosophy and by the looks of it, there is some fun involved, too.United's players were pictured today on each other's backs taking part in some kind of team building exercise (see below).

Lukaku, being the beast he is, was usually the one carrying his teammates and he's now posted a pretty hilarious picture on Instagram from the drill involving Bailly.

In the post below, Bailly is looking pretty menacingly at Lukaku, to which he joked: "Eric relax we're teammates now💯.. #ThatLookTho.. #MUTOUR #REDROM #MUFC."

There are not many defenders that scare Lukaku, but Bailly has proved over the past year that he isn't one to be messed with.

The Ivorian is expected to partner Lindelof at the heart of United's defence next season in a partnership that boasts speed, strength and aggression.