The Black Cats, who were beaten 4-3 at home by Chelsea on Wednesday, have won just twice in the Premier League all season and sit bottom of the table.
However, Dossena was buoyed by the performance against Jose Mourinho's men and is confident that he and his team-mates can get results when facing sides of lesser quality - into which category he argues that Saturday's opponents fall.
|14/1||Sunderland are 14/1 with William Hill to beat Tottenham 2-1|
"We know Chelsea are a great team. I know Tottenham are good but I don't think they're as good as Chelsea.
"We have to show the same heart and same character because it's a very important game."
Even a victory over Tottenham would not pull Sunderland out of the drop zone, although three points could lift the club to 18th if results go their way.
"We've got another chance on Saturday to close the gap on the teams in front of us," added Dossena.
"We kept going [on Wednesday] because the mentality here is perfect. The fans are behind us and we want to win for them. At the end of the day, we didn't get them any points but the mentality here is strong."