It has not exactly been the ideal start to life at Manchester United for Alexis Sanchez, with even Jose Mourinho admitting recently that his January signing has failed to make a real impact thus far.

“What is wrong is that he came at the worst moment of the season, in the winter market,” Mourinho claimed. “That’s why I don’t like the winter market very much. I think it was a chance that we didn’t want to lose and we made it, but we don’t believe a lot in the winter market.

“For sure, next season will be better for him.”

But, as United prepare to face Sevilla in the second leg of their Champions League round-of-16 clash on Tuesday having drawn 0-0 in Spain, they need to start getting more out of the former Arsenal and Barcelona attacker.

His United career is still in its infancy, and his natural game has yet to convincingly match up with his new team-mates’ style. Beyond an FA Cup win at Yeovil Town and his home debut against Huddersfield Town in early February, Sanchez’s contributions have been somewhat covert to this point. Even during their current three-match winning run, the 29-year-old’s influence has been minimal.

However much an initial difficulty might have been expected, Mourinho has previously admitted that part of the reason they signed Sanchez was his potential to make a real difference in Europe.

“Alexis has a level that my attacking players don’t have,” the manager said shortly after the Chilean’s arrival at Old Trafford. “Alexis played Champions League for a few years with different clubs, at least one club that is feeling the responsibility to win it when he was at Barcelona.

“Of my other boys, [Romelu] Lukaku is in the first season in the Champions League, [Marcus] Rashford, [Anthony] Martial, [Jesse] Lingard, just a few matches. We don’t have many with that know-how.

“Part of Alexis’ talent as a player is that he knows what the Champions League is and that is important when you go to the knockout, then the semi-finals. It is for players who know how to compete at that level.”

In the league Sanchez has made little difference to the cause, but any hopes of toppling runaway leaders Manchester City had already long gone before he arrived and he was never expected to slot straight in and shoot United to the brink of an improbable comeback.

It is in the Champions League that his first six months were always going to be judged most markedly, and Tuesday’s Old Trafford fixture is the biggest of Sanchez’s United career so far as a result.

United courted plenty of criticism for their approach at the Ramon Sanchez Pizjuan three weeks ago, but the stage is now set for Sanchez to be the difference-maker when it counts.

He even has the potential bonus of not having Paul Pogba under his feet, with the Frenchman having played only a minimal part in training on Monday following Friday’s collision with Scott McTominay which left him with a gash in his leg. There is a school of thought that Sanchez’s teething problems have come in part due to him wanting to occupy the same space which Pogba favours, but that cannot be claimed to be an issue if the midfielder is absent on Tuesday.

This clash ought to be the one in which everything is in his favour, and if Sanchez gets it right then former United star Lou Macari agrees he could make all the difference going forward in the competition. “Beforehand we never looked like a team that could win the Champions League, but with him there stranger things have happened,” Macari told Goal recently.

“There wouldn’t be many United supporters before saying there’s an outstanding chance of us winning the Champions League, but when you sign somebody like him it can be the turning point in your season in the biggest competition there is.”

Sanchez has another four years on his deal beyond this season, so he will have plenty more chances to impress, even should United fall short this time around. But he could really do with kick-starting his United career now, and there is no better nor more fitting stage on which to start repaying the club's massive salary outlay than the one which presents itself on Tuesday. The honeymoon period is over