3 things to watch in Chelsea's visit to Manchester United

Chelsea heads to Old Trafford to take on Manchester United on Sunday in what is a key match for both teams as they grapple for spots in the Premier League's top four. The Blues won the first match 1-0 at Stamford Bridge.

Antonio Conte and Jose Mourinho have famously traded barbs throughout the last couple of years, but there's plenty to keep an eye on besides the two managers. Here are three things to watch in Sunday's matchup:

The curious case of Paul Pogba

Back when Sir Alex Ferguson was giving his players the hairdryer treatment, there was no doubting who had the power in United's locker room. Brutal but effective, the fiery Scot kept his ranks in line by never relenting his control, but Mourinho hasn't been able to replicate that feat. Some reports claim Mourinho is now in a power struggle with Paul Pogba ... one he will all but certainly lose.

The Frenchman has fallen out of form and thus out of favour, but will likely feature in midfield on Sunday in the absence of Ander Herrera. Pogba is far too valuable for United to ever consider selling, and Mourinho would do well to realize that and do what managers are paid to do - manage their star men.

The crux of the issue is that Pogba's need for freedom - which worked a treat with Juventus in the touch-slower Serie A - is a luxury Mourinho cannot afford to give him. It's not for a lack of trying, as the Portuguese manager took pride in attempting to restore the entertaining, attack-minded football that Ferguson brought to the club, only to see his plans fall apart due to the fragility of his side's defending.

Mourinho resorted to team-first defensive football this season - the same sort he criticised Conte for in the past - and it worked: United has conceded just five goals at home. But Pogba's play has suffered for it. Lest he lose his spot to Scott McTominay, the Frenchman will need to adapt his own game to Mourinho's current needs. This may be his last chance to do so this season.

Mourinho's alternative option? Mask frailties by trying to outscore his opponent.

War of words? Not the talking point

Much has been made of the feud between Mourinho and Conte, and it's worth taking a trip through some of those highlight-reel moments. Whether it was Conte calling Mourinho a "small man" or Mourinho suggesting the Italian was involved with the Calciopoli scandal, there's no love lost here. But you can bet neither spent too much time thinking about the other in the build-up to this tilt.

Instead, each will have spent that time thinking about how to get one over on the other where it counts: on the scoreboard. Conte's Chelsea is coming off the back of a strong 1-1 draw against Barcelona, in which Eden Hazard was again used as a "False 9" and the tactical talking point will be how the Belgian is utilised in this encounter. If you ask Hazard, he much prefers to play on the left wing, opening the door for Alvaro Morata to return to the starting XI.

Morata scored the winner between these two sides the last time they met and Mourinho will certainly plan for the Spanish striker's presence. But he'll also need to keep an eye on Willian, who has found an elusive vein of consistency to his play of late - the Brazilian was certainly expressive against the Blaugrana and could cause United similar problems.

While the two pontificate on the sidelines, keep an eye on Chelsea's attacking line and how United attempts to stifle it. That's the real war in this matchup.

Morata vs. Lukaku, Round II

Speaking of Morata, this Sunday's tilt marks the second time he and fellow striker Romelu Lukaku will meet in Premier League play following their big-money moves last summer, and questions will be asked of both as such. Morata, who dyed his hair red in anticipation of a move to United, and Lukaku, who spoke often of his dream to return to Chelsea, have both endured up-and-down seasons, with injuries plaguing the former and a lack of form, the latter.

There's little separating the two strikers, on paper: Morata has 12 goals and five assists in 33 matches across all competitions to Lukaku's 20 goals and five assists in 42 appearances, good for an average of 0.5 goals per 90 minutes for both players. The Belgian has featured in 954 more minutes this season, which explains the 10-goal lead, but both have proven potent on their day. They are also equally adept at getting involved in attacking plays, with Morata averaging 1.4 key passes per 90 minutes to Lukaku's 1.2.

So fans wearing blue or red need not envy the other before the final whistle, though if one proves the difference by the end of this next 90-minute bout, you can surely bet there will be plenty of rumination regarding the value of the two.

(Photos courtesy: Getty Images)