Sam Allardyce has warned West Ham they are not yet safe from relegation.
Six wins from their last 10 games has seen the Hammers climb away from trouble and they are currently seven points above the drop zone.
But weekend wins for the likes of Fulham, Cardiff and Crystal Palace have got the Upton Park boss looking over his shoulder again.
"The results some of the teams below us pulled off, some surprisingly, means we are not mathematically safe," he said.
"If they then get back-to-back wins you have to look down and say we're not quite there. We've got five very tough games to go, we've got to try to pick up as many points as we can."
Those five matches start with Tuesday night's trip to Arsenal, not-so fresh from their gruelling FA Cup semi-final win on penalties against Wigan on Saturday.
Gunners chief Arsene Wenger admits many of his players are suffering with knocks and fatigue following their Wembley exertions, and Allardyce will be looking to take advantage at the Emirates Stadium.
"We all suffer with spells of injuries and when players can't recover in time and we all know that weakens our team, we had a similar spell in December and it makes your life very difficult as a manager," he said.
"Certainly with Arsenal's game-load and some of those injuries, yes they will be weaker than they possibly could be.
"But they've kept a Champions League place for all these years with a squad of 25 players and nearly all are internationals, and they are playing at the Emirates, so whatever difficulties they have it's still a hugely tough fixture for us.
"Whatever team Arsenal put out we will have to play at our very best if we are to get a result, particularly on their own patch.
"If we can seek an advantage by those problems they have then that gives us a better chance but it won't be any easier than it's ever been at the Emirates.
"The fatigue may happen but it may happen later in the game, not at the beginning, so we will have to be on song and totally focused on what we have to do."
Wenger remains under pressure to end Arsenal's trophy drought, as well as fighting off the challenge of Everton for the fourth Champions League spot.
But Allardyce feels the Frenchman can silence the critics by finishing the season with both.
"The man's career history speaks for itself," said Allardyce.
"People may have been disappointed that he hasn't won anything over the last few years but he can put that right this year with an FA Cup final appearance.
"A lot of the focus is finishing in the Champions League but also making sure they win the FA Cup. And if he does both, compared to the other years, he will have had a more successful season."