Senegal international Sakho joined the Hammers in 2014 from Metz and he was a regular first team fixture in his first two seasons, making 44 Premier League appearances and scoring 15 goals.
However, injuries and a lack of form have severely limited his playing time ever since and there were several reports this summer linking the 27-year-old with a move away after falling down the pecking order at the London Stadium.
The Guediawaye-born star, who has only earned seven international caps, was unable to secure an exit and, for the time being, he will have to battle for game time at West Ham until the January transfer window opens.
Sakho proved his worth in the last league game after coming off the bench to score the winner in the 1-0 victory over Swansea City and Zabaleta is adamant his team-mate will play a big part for the club this term.
"Diafra can have a big impact for us because he's a great player, but it is all about confidence," he told the club's official website. "He's not been playing much in the Premier League aside from coming on for a few minutes, and his only starts have been in the Carabao Cup.
"This is what you expect from players like this who, even if they are not starting the games, they come on and give 100 per cent, even if it is only for ten minutes. He did that against Swansea, so I'm very pleased for him."
West Ham return to action on Saturday with a trip to Turf Moor to take on Burnley and the Hammers have won their previous five meetings against the Clarets - the most recent a 2-1 victory in back in May.
Sakho could be handed a starting opportunity for the clash and punters may decide to use their free bet on the striker firing his side to what would be only their third league win of the season.