With the game tied at 0-0, the French defender came to the rescue as he poked home an unlikely winner in the 72nd minute.
It was arguably an undeserved winner for Arsene Wenger’s side, after they had been hugely unconvincing in the game at the Emirates.
Win they did though, with the result taking them two points clear at the top of the table, and Walcott has praised his teammate, saying he produces massive goals at massive moments.
“He joked that he only scores against Newcastle, but he does produce massive goals at massive moments,” he told arsenal.com.
“There was a sense that he just lifted his game in the last 30 minutes. I could tell how hard he was working and how much he wanted the team to win.
“The fact that he goes forward on every corner shows how much of a massive threat he is. He got the goal he deserved and then we managed to hold on with our back four, so it’s another clean sheet for Petr.”
Koscielny’s goal against Newcastle continued what has been a fine campaign so far for the defender.
He has been highly impressive in the heart of the Gunners defence, with pundits such as Thierry Henry and Rio Ferdinand saying he is the best defender in the Premier League.
The stats certainly back him up as well, with him having made and won every one of the 65 interceptions he has made, a tally that beats every other defender in the league.
Saturday’s win showed his offensive qualities as well, and Arsenal will be hoping he can have a similar impact again in future.