The veteran Finnish goalkeeper joined the Hammers in the summer after spending around 15 years with Bolton and has already kept three clean sheets in the East London club's return to the Premier League.
Jaaskelainen is thrilled to be back playing first team football after Adam Bogdan was preferred to him late in his Reebok Stadium career and vows to keep up the high standard he has set for Sam Allardyce at Upton Park.
"I try to work hard throughout the week to make sure I am ready for the game on Saturday," he told West Ham's official website.
"It helps that I have played in the Premier League before and I already know Sam (Allardyce) and his backroom staff.
"I really like the way they look after their players and hopefully I can repay them by keeping my performance levels at the same heights they have been so far this season.
"As a goalkeeper it is all about consistency."