5 Truths: Sanchez the saviour, Costa the catalyst, and Arsenal's liability

Where to start with what must be one of the most ridiculous, and entertaining, finishes to a game in Premier League history? When the fourth official raised his board to show seven minutes of added time in the match between Arsenal and Burnley it was if he was signalling for everyone involved to lose their heads. Francis Coquelin kicked off the madness with a foul on Ashley Barnes in the box on 92 minutes to give away a penalty, which Andre Gray converted. Thoughts immediately wandered to a famous game against Liverpool in 2011 when Robin van Persie scored an injury-time penalty but Emmanuel Eboue then fouled Lucas Leiva, allowing Liverpool to equalize after 102 minutes.

This time it was the reverse effect. Just when Arsenal were nursing an intense pang of frustration - with Arsene Wenger being sent to the stands for his reaction, not before pushing fourth official Anthony Taylor - Ben Mee was penalised for a high boot on Laurent Koscielny, allowing Alexis Sanchez to Panenka it home after 98 minutes. Complete chaos. But at the end of it Arsenal secured a vitally important three points which puts them second ahead of Liverpool and Tottenham – and ultimately it was thanks to Sanchez, again, who now has 15 goals and seven assists in 22 Premier League games.

He had missed two penalties before Sunday’s match but the main driving force behind Arsenal’s title challenge, or at least their pretence at one, did it again. What is that line about keeping your head while all about you are losing theirs?

The contrast between last week's sparkling 3-0 victory over Leicester City and this dour, and frankly lucky, win over Hull is remarkable. Chelsea looked flat and tired, despite not being in Europe, and their star players couldn't really create anything against a disciplined Hull side.

Thankfully for them the man of whom so much has written came to the fore. Diego Costa took his goal well, producing a telling celebration in the process, but he worked hard for the team and could have had a couple more were it not for a good save here or a poor pass there.

He was rightly named man of the match and even if he were to leave in the summer there is plenty of history left for him to write in the next few months,

If Wenger was in apologetic mood after his confrontation with Taylor, he was in no mood for niceties when it came to his own player, Granit Xhaka, who was shown his second red card of the season for violent conduct and will now serve a four-game ban after he lunged in on Steven Defour in dangerous fashion. In fact it was Xhaka’s third red of the season for club and country and seventh in three seasons.

“He has to control his game,” was the message from Wenger,” and not punish his team. As well as red cards against Swansea and now Burnley, the summer signing has also given away penalties against Stoke City and Bournemouth. He looks a talented player and has stepped up admirably in the absence of Santi Cazorla, giving Arsenal some control and penetration from midfield, but Xhaka is a liability. His replacement, Coquelin, gave away the penalty and Xhaka must have been the most relieved man in the stadium when Sanchez dinked his spot-kick home.

One of the hallmarks of Leicester's remarkable title-winning campaign was their consistency, both at home and away. However, this season has seen Claudio Ranieri's side slip to a very damaging record of draws and defeats with 26 goals conceded in their last 13 away games in the Premier League. Factor in just one clean sheet over the course of those games and the Foxes' problems become very stark.

Without an away win since April, Ranieri must somehow find a solution with his side now languishing down in 15th place, just five points above the relegation zone and six off bottom-placed Sunderland. It was not just another poor result for Leicester; the team looked flat and lifeless for long stretches of the defeat at Southampton with the vibrancy of last season a very distant memory.

Marco Silva will be disappointed with the way his team conceded the two goals that saw Chelsea defeat them on Sunday but he can be immensely proud of the way they played throughout the game. Hull were well organised as they matched Chelsea's system and they deserved far more.

In the second half Hull dominated possession and they should have had a penalty when Abel Hernandez was tripped by Marcos Alonso. Chelsea fans will argue they too should have had a spot-kick, and Curtis Davies should have sent off, but neither were as clear cut as the Alonso foul. Thibaut Courtois had to be called into action with far more regularity than he would have expected and for the most part Chelsea struggled to break Hull down.

This is just the latest in a string of impressive performances by Hull since Silva took over, and this without the talismanic Robert Snodgrass. The Portuguese was doubted by many when he took over but Hull will certainly feel confident of survival based on the past couple of weeks.