With thousands of Cologne fans either travelling without tickets or purchasing tickets in home sections of the ground, local police made the decision to delay the start of the game due to crowd safety.
There were some doubts that the game would go ahead, but it was eventually given the green light to start at 9.05pm and the home side got the win they needed after a sluggish start.
The visiting masses were celebrating when their team took an early lead through Jhon Cordoba’s 40-yard strike and maintained it until half-time, but substitute Sead Kolasinac’s volley, Alexis Sanchez’s superb curler and Bellerin’s 82nd-minute goal saw Arsenal to a 3-1 win.
“We had a bit of a slow start, and conceded an accidental goal,” said Wenger. “After that it was important not to concede a second goal and not to panic.
“We wanted to inject a bit more pace into the game in the second half, and from there I think we controlled the game and it was a convincing win in the end.”
Sanchez looked set to join Premier League rivals Manchester City in the transfer window but stayed put after Arsenal’s move for prospective replacement Thomas Lemar fell through.
Back in the starting line-up for the first time, the Chile star showed his quality by cutting in from the left to fire home the second from the edge of the box.
“We want him here,” said Wenger. “He’s a fantastic football player but physically, he is just coming back.
“It’s always in his locker to deliver something special, which he did.”