WATCH: Alexis Sanchez tries to hide his laughter as Arsenal teammates suffer another humiliation

It wasn't a great night for Arsenal supporters.

Those that turned up at the Emirates did so knowing full well that their side were all but out of the Champions League after their 5-1 mauling in Munich a few weeks back, but still, things couldn't get any worse, right? Erm... wrong. Despite a spirited first half performance from the home side - one in which we Theo Walcott gave them the lead - things swiftly fell apart in the second half. Bayern Munich were awarded a penalty after a Laurent Koscielny was deemed to have fouled Robert Lewandoski. Not only that, the official behind the goal appeared to convince the ref that this was worthy of a red. Lewandowski scored it, and four more Bayern goals followed. 5-1 again, and 10-2 on aggregate to the German champions. Again, things couldn't get much worse, right? Erm... wrong again. With Alexis Sanchez substituted during the second half, camera lenses were briefly trained on the Chilean as he watched the final moments of the game from the Arsenal bench. Although we've no idea what his conversation with Petr Cech was about, the fact that Sanchez appears to be smiling in the immediate aftermath of Bayern's fifth goal understandably won't sit well with some Arsenal supporters. https://twitter.com/SvpremeShinji/status/839226683878166528 Of course, there could be an innocent explanation for it, but the timing wasn't great for Sanchez. Plenty of football fans had already formed an opinion. https://twitter.com/keith_nelis/status/839226678031302658 https://twitter.com/SuperJWilshere/status/839229313241186308