The France international believes his team-mates now possess the "fighting spirit" and the team's technical quality has been raised since the arrival of Mesut Ozil
Arsene Wenger’s men head into the fixture two points clear at the top of the Premier League with a game in hand over second-placed Liverpool.
The Gunners will also be buoyed by their 1-0 win over Borussia Dortmund in the Champions League on Wednesday and Sagna believes his team-mates now possess the right mentality to compete with the title challengers.
"Technically we had a very strong group of players, which is now even stronger with Mezut Ozil,” said Sagna.
“But we were missing the physical impact in the Premier League. We were missing the fighting spirit.
"Maybe we thought our technical ability would be enough to make the difference. This time, we don't fear anyone."