The St James' Park outfit have managed just seven Premier League wins all season and are only two points clear of danger, but Diame believes they are not too far away from being a winning side.
He told the Chronicle: "The team needs to stay confident and believe in what we are doing. There are some little details we need to change and make sure we're focused because we've dropped too many points already.
"We've been winning in some games and ended up drawing at the last minute. It's just small details and those details must come at the end.
"We just have to keep going and stay focused from the first minute until the end."
Saints are just one place and one point behind Newcastle in the standings and Diame is well aware of just how important this weekend's fixture could be at the end of the season.
"They are in the same situation as us, so it is a massive game," he added.
"It's an important one, we need to give everything on the pitch."