Graeme Souness warned Leicester City that they need to up their game to reach the Champions League after the Foxes were crushed 4-2 at home to Newcastle.
Brendan Rodgers' side were comprehensively beaten at the King Power Stadium, with goals from Joe Willock, Paul Dummett and a Callum Wilson brace putting Steve Bruce's side 4-0 up deep into the second-half.
The Foxes threatened a comeback with goals from Marc Albrighton and Kelechi Iheanacho but it was too late for Leicester - who missed the chance to go eight points clear of fifth-placed West Ham.
Rodgers' men now face a daunting league run-in with trips to Manchester United and Chelsea coming before the visit of Tottenham on the final day of the season, with Souness claiming Leicester could lose all three if they play like Friday's display.
He told Sky Sports: 'If that's Leicester for the last three games of the season, they won't win them. They need to get back to the high intensity of football.
'They didn't start right. They're a team that have everything to play for in terms of finishing in the top four, keeping that momentum, that winning feeling for a cup final that's coming up. And they didn't start right.
'The tempo was set by Newcastle by being first to the ball. Leicester thought they would win the game and it was only a matter of time. Newcastle were convincingly the better team for an hour and deserved to win the game.'
Leicester suffered a horrendous collapse after the coronavirus hiatus last year, winning just two from their last nine league games to fall from third to fifth and miss out on Champions League football.
Now the fifth-placed Hammers can move just two points behind Leicester should they beat fellow continental football contenders Everton at home on Sunday.
Meanwhile, Thomas Tuchel's Chelsea - who play Leicester in next weekend's FA Cup final at Wembley - can leapfrog Leicester into third should they beat Manchester City on Saturday.
Souness continued to slam Leicester's start to the match and reaffirmed the point that this was a major opportunity missed to stamp their authority on a top-four spot.
He continued: 'It's one of the last things you hear from the coaching staff or from the manager, let's start right. I don't think this Leicester side didn't get anywhere near that for an hour.
'Newcastle are a team where it's worst case scenario, worst case scenario. You have to get the points from somewhere. The game was gone before it got going. It's hard to get it back.'