The German defender believes that his side's current run of form will help them to overcome Reading on Saturday.
The Gunners take on Championship side Reading in the semi-finals at Wembley on Saturday hoping to edge a step closer to the successful defence of a crown they claimed last season.
Arsene Wenger’s side are currently in a fine run of form having won 16 of their last 18 games, a run which has seen them rise to second in the Premier League table.
That momentum has left them as firm favourites for the tie against Reading, and Mertesacker says the side are brimming with belief heading into a crucial fixture.
“Our level of confidence and with the team in good shape at the moment, I’m very confident,” said the German defender.
“The energy is really great in the team, we have a fantastic squad and the most important thing is that feeling. We will have to face the expectations and pressure.”
The World Cup winner has also reflected on last season’s FA Cup fixtures and how the side has learned from that experience.
Wigan Athletic ran them close in last season’s semi-final, with Mertesacker conceding a penalty and scoring in the game, while they also had to fight back against Hull City in the final. The last-four showdown in particular is one that Mertesacker won’t be forgetting for a while.
“That [game] was really strange for me,” he added.
“To foul a player when we got the penalty against us, I then had to put something right at the other end. I put something in my head of, ‘Now it is your turn’ and I kept going like that. Finally it happened [and] we went through to penalties.”