West Ham are looking to improve on the draw over Walsall on Saturday when they face Wimbledon on Tuesday and Alan admits:
"It was a great couple of days for Norwich and West Brom and that is what is the biggest disappointment because I think both these teams are catchable - but we have given them another good weekend.
"We can't afford to do that once more in this run-in; one more slip up, especially in your home games, gives the momentum to the two clubs that have got away.
"If someone doesn't come out and challenge them they are going to get a free run at it and then everybody will be kicking themselves.
"We have to be on guard - us, Sheffield United, Sunderland, Ipswich, Reading, everybody - to make a fight of it."
A win would tuck the Hammers below West Brom and Alan adds:
"If we can go third that will give us the momentum to go to Sunderland.
"What an opportunity that is if we win - we can't pass it up.
"I went there yesterday and that is going to be a tough game for us - we have got a huge mountain to climb on Saturday against them.
"It will be very important to go there on the back of a win."
Looking at Saturday's stalemate, he says:
"It was a disappointing day, but to be honest it was the first one for a while from us.
"That doesn't make it acceptable, though, and we are getting our heads down today to make sure we don't slip up against Wimbledon.
"We are not banging the goals in as we should be and we did not create the chances on Saturday that we have in the previous few games.
"But certainly we haven't taken enough and we are looking to the players to get the goals for us.
"When the other team comes and tactically shuts up shop you need that goal to break them down and bring them out.
"Once you do that you have got more opportunities to score, but we haven't scored an early goal at home and that is the problem.
"The fans were terrific but we gave them nothing - they won't get off their seats when there's nothing to get off their seats for and we didn't make a tackle for about 30 minutes.
"The place will come alive if they get the right product in front of them, but we didn't give them that - Walsall came to slow the tempo down, which is exactly what you would expect from a team that hasn't had a result for a while.
"It just shows that task in front of us is massive; we have to be better than most other teams who are happy to come here for a draw, but people have to understand we have to build brick by brick and we played into their hands in a game that people said was a home banker.
"We have another such game against Wimbledon on Tuesday and they will play a similar way but people have to understand we have to be patient.
"It only took three or four players to put in sub-standard performances for us to play like as we did on Saturday.
"To have dropped 24 points at home does not mean we have a complex - but that sort of performance is not acceptable."
As to whether Bobby Zamora's disallowed 'goal' was offside, he says:
"I think it was tight and I have seen them given so it was disappointing.
"But I won't let the players forget their performances - I want it to hurt, and it did hurt.
"Hopefully the players will respond to that."
Alan refuses to use Hayden Mullins' premature departure from Saturday's game as a contributory factor in the draw, and he adds:
"Andy Melville is a senior professional and we wouldn't look to that as an excuse.
"Hayden will be out for the Wimbledon game but he will be in contention against Sunderland."
Kevin Horlock returns to the squad for the Wimbledon game from injury and Matthew Etherington is back after a ban.
SQUAD: Bywater, Srnicek, Repka, Melville, Dailly, Harley, Harewood, Carrick, Connolly, Deane, Zamora, Reo-Coker, Nowland, McAnuff, Etherington, Ferdinand, Carole, Horlock.