Manchester United look like a force to be reckoned with this season judging by how easily they swept aside West Ham on Sunday.

Goals from Romelu Lukaku (2), Anthony Martial and Paul Pogba secured a convincing 4-0 victory at Old Trafford to make the best possible start to 2017/18.

Jose Mourinho has recruited well this summer by bringing in Lukaku, Nemanja Matic and Victor Lindelof, and it's expected one more signing is on the horizon.

But while United are blessed with plenty of midfield and attacking options, a few concerns remain as to the quality of their defence.

New full-backs have long been on Mourinho's wish list, with Serge Aurier and Danny Rose the most recent players to have been linked with moves to Manchester.

Antonio Valencia is one of United's most consistent players at right-back but at 32-years-old, age will start catching up with him.

As for at left-back, Daley Blind, Luke Shaw and Marcos Rojo have all tried and failed to nail down the spot as their own.

Even another centre-back wouldn't go amiss at United given Chris Smalling and Phil Jones are both renowned for making costly mistakes.

One player fans would love to see arrive is Bayern Munich's Mats Hummels, who has previously been linked with the Red Devils.

Hummels, 28, is currently one of the world's finest centre-backs and exactly the calibre of defender United need.

And for a split second on Thursday, the club's fans thought they'd actually signed him.

Juan Mata recently called upon his fellow professional footballers to donate 1% of their wages to charities supporting underprivileged youngsters around the world.

Hummels has joined the cause, which Mata confirmed on Twitter with a potentially misleading tweet (see below).

By saying "Welcome to the team", Mata inadvertently suggested United had signed Hummels, which sent fans into meltdown.

TWITTER REACTS

Awkward - Mata might want to choose his words more carefully the next time he confirms a world-class player has joined his cause.

There's no chance of Hummels signing for United this summer, of course, but Mourinho is still on the lookout for a fourth addition.

Who that will be remains to be seen, but there are rumours that Mourinho's fourth and final signing might already be at the club.

Zlatan Ibrahimovic is reportedly in talks over a new short-term deal after showing promising signs in his recovery from a serious knee injury.