Diop joined the Hammers from Greek giants AEK Athens last week.
“I am confident we can be promoted because we have quality players,” he told the club’s official website. “They are Premier League players.
“If you saw how they did at Nottingham Forest, you can see they played well and scored four goals. If we continue like this, we can return to the Premier League at the end of the season.
“I saw the game against Leeds. I like the atmosphere, the fans push the players, the team. It is good to feel something like this. They give you motivation to go forward and give everything. It is helpful.
“We all have to talk and be close. When we come to the matches we must all give everything for West Ham.
“There are a lot of games in the Championship, two or three a week, but I am focused on getting stronger and helping the team to pick up points every time we play.
“I will work hard. The Championship is more demanding than the Premier League and it is different but I want to play.”
