Dominic Calvert-Lewin believes Everton have to "keep believing" after his winner reinforced their European credentials with a hard-earned victory away to Champions League hopefuls West Ham.
After being fourth in the Premier League at the turn of the year, a run of six wins from 18 saw the Toffees slip to eighth.
But Ben Godfrey's slide-rule pass allowed Calvert-Lewin to score his 16th league goal of the season in the first half at London Stadium.
And manager Carlo Ancelotti's decision to play with three centre-backs was justified as his side defended resolutely to secure a second straight away win having also won 1-0 at Arsenal last month.
Everton remain eighth but are now one point behind seventh-placed Tottenham and three behind fifth-placed West Ham - with a game in hand on both.
The striker said: "I think every game is getting more important from now until the end of the season, so we simply have to keep believing and go into every game trying to win."
Toffees boss Carlo Ancelotti added: "It was a vital victory, if we don't win here we are out of the fight for Europe.
"There was pressure on the game but we managed the game well. We played defensively at the top, really good, and were really dangerous on the counter-attack."
For the Hammers, this is a big blow to manager David Moyes' hopes of again leading an unfancied team into the Champions League having done so as Everton boss in 2005.
Newcastle won at fourth-placed Leicester on Friday but this defeat keeps West Ham five points off the top four with just three games left.
A Europa League spot would be some consolation for Moyes and his former club aim to join West Ham after claiming their 11th away win in the league this season - and their fifth in London.