Arsenal defender Per Mertesacker has admitted, as quoted by the Guardian, that Alexis Sanchez's injury problems have had a big toll on the club this season because of the energy and quality he brings to the side.
This year, Sanchez has not been able to replicate the consistent success of his first season in England last term, when he scored 25 goals in 52 appearances in all competitions.
That has been due almost exclusively to injury - the Chilean missed two months of the season during the hectic period of late November until the end of January, and struggled for form in the weeks following his return.
However, the 27-year-old appears to have hit top gear again in recent weeks, and his brace in the win over West Bromwich Albion on Thursday night means he has netted five goals in his four appearances in April.
Despite his injury troubles and accusations of second season syndrome, Sanchez has a virtually identical goals-to-games ratio this season as he boasted last campaign - a goal every 2.25 games this term compared to one every 2.08 matches in 2014-15.
Those two returns are the best of Sanchez's career, and despite insisting the club coped well with his absence, Mertesacker is under no illusions that Sanchez is crucial to Arsenal's game.
The German said, as quoted by the Guardian: "When he was out, I think the statistics were not that bad for us – I think we played 10 games and won seven. But, obviously, if he is on the pitch, he always creates space for other players because he draws so much attention and that is the key to any team.
"He is a key member of our team and if he is fully fit, he makes the difference and that is always the case. Over the whole season, normally we need him healthy.
"He is the type of player who makes the difference and even when he is in Chile playing two World Cup qualifiers, he will be back on track in the right time, when he has had just two days’ rest in between. He is that type of player who gives everything to the team. Those team members are well appreciated."
Sanchez's double on Thursday strengthened the Gunners' grip on a Champions League spot and moved them back above Manchester City into third in the table.