They lost 1-0 at West Brom on Saturday and slipped to sixth after Liverpool's 2-1 win over Manchester City on Sunday
The Saints host Crystal Palace on Tuesday battling to keep pace with the Champions League places and defender Fonte wants a response.
"As a club we need to stick together because we've done fantastically until now and there are still 11 games to go
We all need to keep fighting," he told the club's official site.
"We need to look at the bigger picture
We're still in a good position and there's a lot to play for.
"We know where we want to be as a club, as a team and as a group of players, so Tuesday's game is massive.
"We conceded another early goal and went the whole game trying to find the target and again we couldn't find a goal.
"That's something that has been happening for a while now, but we need to keep strong and believe in each other
Without putting too much pressure on the guys up front, we need to - as a team - pull through this."
Victory lifted the Baggies to 13th in the Barclays Premier League to put them on course for survival and they have lost just once in their last 11 games in all competitions
It was the fourth straight clean sheet and head coach Tony Pulis has seen them keep seven shut outs in his first 10 matches in charge.
Albion go to Aston Villa for the derby on Tuesday - before returning for the FA Cup quarter-final on Saturday - and goalkeeper Ben Foster is ready for two huge games.
"It's a big week, we always knew it
If you'd offered us four points from this week and a quarter-final win we'd have taken it
Hopefully we can take six points," he told Albion Player.
"I don't care what position in the league you're in, a local derby for the fans is one of the most important games of the season.
"It's a big game on Tuesday and then we can look forward to the quarter final on Saturday."
Source : PA