After their 5-0 thrashing by Manchester City, Hangeland has not lost appetite for the battle.
The Norwegian defender said: "Obviously you are low when you get beat 5-0. It was a difficult game for us.
"But what can you do? You have to pick yourselves up. There is no point dwelling on any game of football, and definitely not a defeat like this.
"We are going back to London to work on training and prepare for Sunday."
Asked if the squad believed they could stay up, the 32-year-old said: "Very much so. We have quite a few games we know we can win. It is still doable and there is a belief we can do it.
"Time is running out a little bit and we need to pick up results."
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