Manchester United open their Champions League campaign on Wednesday with a group stage clash against BSC Young Boys, champions of the Swiss Super League in 2017-18.

With Valencia and Juventus also in the same group, the fixture is a must-win for United, who can’t afford to drop points before even playing the other two big sides.

Here’s a look at the players charged with getting all three points on Wednesday night in our key battles.

Guillaume Hoarau vs Romelu Lukaku

Guillaume Hoarau has started the season on a tear, scoring four goals in six Super League appearances. Of course, it’ll be a huge step up playing against United, but the confidence will be flowing for the former Paris Saint-Germain striker.

He was instrumental in Young Boys qualifying for the group stages of the Champions League, scoring both goals in their 2-1 second leg win away to Dinamo Zagreb after they’d fallen behind and looked in danger of being knocked out.

And with the way the Red Devils have defended at times this season, maybe he’ll be fancying his chances.

Like his opposite number, Lukaku has been in fine form to start the season, scoring four times in five club appearances, and six in six in total for club and country.

However, he’s missed some high-profile chances that could have changed the narrative of United’s campaign so far. And as the club’s lead striker, the scrutiny will always be on him. His performances in Europe, first in a potential banana-skin tie, will go a long way in enhancing his reputation – or sinking it. As always, the spotlight is on the big Belgian.

Miralem Sulejmani vs Marcus Rashford

United have the more famous Serbian footballer in their ranks but Young Boys winger Miralem Sulejmani will be looking to send a reminder of his own quality. He and Nemanja Matic were once united in disappointment, failing to make the final cut for Serbia’s World Cup squad in 2010.

Sulejmani was a promising winger for Ajax then, but his career hasn’t quite gone to script since. He moved to Benfica – where he was briefly teammates with Matic – but suffered a gruesome injury.

However, he’s been resurrecting his career in Switzerland since 2015, and he’s started this season with three goals and five assists in nine total appearances.

All indications are that Sulejmani’s opposite number on Wednesday will be Marcus Rashford. The young Englishman’s form and place have both come under intense scrutiny in recent times, with manager Jose Mourinho hitting back at perceptions that he is stifling the youngster’s development.

However, Rashford’s status as a backup rather than an automatic first-choice player has to do with his own form as well. The chopping and changing hasn’t helped, but he’s also shown only flashes when given a chance. He’s in form – two goals during the international break; now, he has to make it count.

Gregory Wuthrich vs Chris Smalling

Young Boys are sweating on the fitness of their 23-year-old centre-back, who has played every minute of their league campaign so far but missed the weekend’s cup tie through injury.

If he’s fit, Gregory Wuthrich will be the man tasked with stopping Lukaku, which will be a good examination of the youngster’s ability. Wuthrich has acquitted himself well against strikers in the Swiss league but the Belgian, never an easy player to defend, will be a step up. The young Swiss defender could be the difference between a competitive game and a rout.

The answer to Manchester United’s long-standing defensive crisis is…Chris Smalling?

Mourinho probably hasn’t quite come to that conclusion, and the Englishman has blown hot and cold ever since arriving at Old Trafford in 2010, but he has added some solidity to the back-line. He looked like the only capable defender in United’s disastrous defeat to Tottenham, and since then has been a stable presence at the back.

At the other end, Smalling has developed into a reliable goal threat from set-pieces, profiting from the attention players like Lukaku, Paul Pogba, and Marouane Fellaini command. The Swiss champions will have to be wary.