West Ham manager Sam Allardyce admitted his side would probably have to win all six remaining games to be certain of booking a place in the Premier League next season.
The Hammers were beaten 4-2 at home on Saturday by Championship promotion rivals Reading, leaving Allardyce feeling that they have no other options open if they want to reel in the Royals, who are in second place.
"We shot ourselves in the foot," the former Bolton boss said.
"There are no more opportunities for us to take a point any more. To keep up with Reading we have to win six on the trot.
"We gifted them three goals. We can't afford to make those errors and that's ultimately why we got beaten."
The win shot Reading back into the title race as leaders Southampton suffered a shock 3-0 defeat at fifth-placed Blackpool.
The results meant Reading are just two points behind the Saints and four clear of West Ham in the scrap to secure the two automatic promotion spots.
Reading boss Brian McDermott refused to get carried away with the victory at Upton Park.
"It's three points, that's all it is," he told reporters. "It's never easy to go 1-0 down here but we stayed in the game, got ourselves a goal and to go in 2-1 up was massive.
"Then in the second half I felt we deserved to win. But I've been around this game a long time so I'm not cock-a-hoop yet."
The Hammers took the lead but two quick Reading goals just before half-time turned the match around in front of the 33,350-strong crowd.
Meanwhile, Southampton were sunk at Bloomfield Road, missing an early penalty before Blackpool made them pay.
Saints manager Nigel Adkins said it was no time to panic.
"We will analyse this in the cold light of day," he said. "We have been in the top two in the league for virtually the whole campaign and so we will just put this game to bed and move on.
"Blackpool closed us down very well throughout and never gave us much time on the ball to play our game.
"Blackpool deserve a lot of credit for their performance and sometimes you just have to accept that."
Blackpool boss Ian Holloway said his team could be on course for a return to the Premier League.
"I am very proud. All of our players deserve the credit to a man," he said.
"Already we are better on points than we were at the same stage when we got promoted last time.
"We have just beaten the best team in the league so I am very pleased because Southampton are used to dominating the game."
The result left Birmingham, Blackpool, Brighton and Middlesbrough level on 63 points -- nine behind West Ham -- with seventh-placed Boro just outside the play-offs on goal difference.
Brighton and Middlesbrough cancelled each other out in a 1-1 draw at the Amex.
"The longer we stay in the top six the better. There were nerves all over the place, but we are still in there so we can't complain," Brighton manager Gus Poyet said.
Boro boss Tony Mowbray added: "With four weeks to go it is very tight obviously, but we have to keep going."
Birmingham won 3-1 on Friday at rock-bottom Doncaster, who are now six points from safety with six games left.
Portsmouth, a point above Doncaster, were crushed 5-1 at home by Burnley.
"It is going to be tough but I still believe that we can do it. We all do. We have to," said Portsmouth boss Michael Appleton.
"I do not mind if it it goes down to the last day as long as we stay up. I am still confident."