Arsenal defender Kolo Toure admits superstition saw him booked during last night's 1-0 victory over Roma.

As the team ran out for the second half, Toure waited for his defensive partner William Gallas, who was having extra treatment, and joined the game after it had restarted without permission from Danish referee Claus Bo Larsen - a yellow card offence.

"I'm always the one that comes last on the pitch and so I was waiting for William," said Toure. "When I came on I didn't know I couldn't come on straight away."

Remarkably, Toure sought to laugh off the incident, adding: "But the good news is that I've learned another ruling, so that is great."

Manager Arsene Wenger defended Toure even though the needless caution puts the Ivorian on thin ice for the return leg at the Stadio Olimpico in a fortnight.

The 27-year-old will potentially miss the quarter-final first leg should Arsenal progress.

But Wenger said: "It's explainable by the fact that Kolo always goes out last. He waited for William but didn't know William had treatment. He didn't know the game had started without them. He was putting on his boots. It is our fault. You have to be ready when the bell rings."