Sunday 1 April 2018 15:50, UK
Marcos Alonso has admitted reaching the top four would be "very difficult" if Chelsea fail to beat Tottenham Hotspur on Sunday, live on Sky Sports Premier League.
The Premier League champions are five points adrift of Champions League qualification with eight games to go, but face fourth-placed Spurs at Stamford Bridge on Sunday at 4pm.
Alonso will not let go of his belief the Blues could still mount a late-season charge without victory in that game - but admits they will be up against it.
He said: "It is definitely a must-win game. Here at Chelsea, we have to fight until the end for every target we can achieve, and next year we have to be in the Champions League. On Sunday, we have to get a win.
"It's a massive game. We have a very important target, which is arriving at the end of the season in top four. Starting on Sunday, it's the first important three points for us.
"It's not over until its' mathematically impossible, but it would be very difficult for sure if we lost."
Spurs talisman Harry Kane is likely to miss the game after damaging ankle ligaments against Bournemouth earlier this month, but regardless of his involvement, replacement Heung-Min Son has taken the mantle of chief goalscorer with both hands.
Alonso is careful not to be drawn into a trap of expecting an easy ride when Mauricio Pochettino's side visit Stamford Bridge, in search of their first league win at the club since 1990.
"Kane is a very important player for them, that's for sure," he said. "But I think they are a very good side physically, with some quality players, and I think it will be a very tough game even without him.
"I don't think the past will have an influence. I don't like stats, I think it will be a different game and we will have to give everything and be fully focused to get the three points."
Alonso has a personal motivation to perform in the final weeks of the campaign, in addition to his collective responsibilities for Chelsea, having made his international debut for Spain in their 6-1 drubbing of Argentina on Tuesday night.
The World Cup is very much in the 27-year-old's mind, who has had to wait his time for recognition on the international stage, but could easily find himself on the plane to Russia in barely two months' time if he ends the season in good form.
He said: "It was a very important day for me. I'm very happy for it, I'm proud to represent my country at a senior level, and I think it's a reward for the good work I've been doing in the last few years. I just have to keep working to keep going with it.
"It's a massive motivation. With the World Cup just round the corner, it's very important to finish the season well, then we'll see the decision the manager takes."
