West Ham boss Allardyce said last Friday that former Paris Saint-Germain and Monaco forward Nene would not come into contention for up to a fortnight due to a lack of match fitness.
However, Carlton Cole has joined Andy Carroll on the sidelines after sustaining a hamstring injury during Sunday's 2-2 Premier League draw at Tottenham, meaning Nene is therefore in line to make his debut at Upton Park this weekend.
Allardyce told the club's official website: "Nene would have probably featured anyway but he will definitely be involved now because we're down to the two strikers with Andy Carroll's injury and Carlton Cole's new hamstring problem,
"Enner Valencia and Diafra Sakho did a fantastic job - like the whole team - against Tottenham. It was just a shame we were not all going out celebrating another victory against Tottenham."
West Ham squandered a two-goal lead to draw 2-2 at White Hart Lane on Sunday, with Harry Kane scoring a last-gasp equaliser.
Allardyce is urging his players to put that disappointment behind them by seeing off Palace.
He added: "Sunday was a bit difficult for the lads to take but we have to take heart out of the performance and go and deliver that performance against a team that has got momentum.
"Let's take it out on them and if we play like we did on Sunday we'll have the opportunity to beat them."
