The League Two side took the lead early in the first half through Aaron Loupalo-Bi's low shot.

The Gunners fought back to make it 1-1, thanks to Viktor Gyokeres' first goal of the season.

Despite coming close several times, Mikel Arteta's men failed to find the winner at Highbury and the tie went to penalties.

It was Bruno Guimaraes who missed the crucial kick for the Gunners.

Conor Haughey then sent Illan Meslier the wrong way as the visitors progressed into the next round.

In the other tie on Tuesday night, Bradford City beat Peterborough 2-0 to qualify for the last eight.