Leeds dominated the first half, with Jack Harrison testing the keeper first from the edge of the box. A big chance for Patrick Bamford followed, with some brilliant play down the right channel between Harrison and Ayling before Bamford whacked the ball off the top of the bar.
Alioski had a couple chances himself, the first being a shot across goal after Klich won the ball high-up the pitch before releasing the Macedonian down the left side. The shot was dragged just wide.
On 34 minutes, Ayling beat Sokratis on the right side before swinging the ball into the back-post. Alioski rose highest before his header was beaten away by Martinez.
Debutant, Robbie Gotts had a great chance fall to him as half-time approached. Klich cut the ball inside from the right, with Gotts swinging a boot at a spinning ball, blazing his strike over the bar.
But the second half was different, Arteta gave his side a kick up the backside who were out-played in the first-half, and the Gunners came out on the front foot.
Nelson came close early in the second half, beating White but is quickly scrambled around the penalty area before eventually being cleared.
Arsenal then hit the crossbar themselves, as Lacazette hit a freekick from 20 yards off the top of the crossbar. Lacazette came again soon after, looking to place a shot past Meslier’s left, with the fellow Frenchman making an excellent low save.
Arsenal then took the lead on 55 minutes, with Lacazette cutting the ball back toward Nelson with the help of a big deflection before Nelson managed to get the fine touch to spin the ball away from the keeper and give Arsenal the lead.
Few clear-cut chances came-up after that, with Meslier making a couple decent saves, while Harrison was unlucky in late attack down the left side with unfortunate deflections ending the attacks.
It was fine margins for Leeds, but they proved what they arrived in London to prove, that they could compete against top teams, on to the next one.