Mertesacker - The key to zonal marking

Per Mertesacker believes the key to zonal marking is an emphasis on attacking the ball.

Martin Demichelis' late leveller at Emirates Stadium on Saturday was the fourth headed goal scored against Arsenal so far this season.

Mertesacker was disappointed to concede from a set-piece but was encouraged by the team's spirited display.

"When you play zonal, you need to attack the ball and try to get the best players out and mark tightly when they are in front of you," Mertesacker told Arsenal Player. "We lacked a bit of that intensity but we suffered a bit, especially in the last 10 minutes after Mathieu Debuchy got injured. It was a bit of a blow for us but we gave everything and came out with a draw.

"It was high intensity from the start. I think we started really well. All the way through, we tried to put pressure on them and tried to create chances.

"I think we deserved to get in front but all of a sudden they got us on the break and scored the first goal. After, we tried and tried and tried. We kept going, carried on and made it happen. In the end we suffered a lot.

"I think you could see that we gave absolutely everything so we are really proud. I think they deserved the draw because they pressed up and pushed really high at the end. It's a bit disappointing but I think the team is in a good shape. We have good players and potential."

Saturday's match was the first of seven in 22 games. Arsenal travel to Borussia Dortmund on Tuesday night and Mertesacker feels that the fixture may come at a good time.

"I think we have to give absolutely everything again to get something out of Dortmund," he said. "They have a good squad, have suffered a few injuries and I think it's good to have them at the start [of the group]. We'll try our best and try to deal with the pressure they will put on us."