Who should Arsenal play in central midfield? Peter Smith takes a look at their options...
Central midfield was long considered an area of weakness for Arsenal but Arsene Wenger now has a number of options in the middle of the park, with Santi Cazorla, Granit Xhaka, Francis Coquelin and Mohamed Elneny all vying for two starting spots. The question is, which pairing is best?
Coquelin and Elneny replaced the injured Cazorla and suspended Xhaka against Middlesbrough on Saturday, stepping into the two holding positions in Wenger's preferred 4-2-3-1 formation.
However, they were unable to inspire the Gunners to victory - and Petr Cech was twice forced into good first-half saves when the visitors found a way through.
So what will Wenger do when he has all four players to choose from? We take a look at how the combinations he's used so far have done…
Elneny and Coquelin
Saturday was the first time Wenger had started Elneny and Coquelin alongside each other since the opening weekend of the Premier League season, when Arsenal lost a 4-3 thriller at home to Liverpool.
That day, Elneny was taken off 67 minutes in, after failing to stop Liverpool's high-speed assaults. He had made no tackles and regained possession for his team just three times.
He was replaced by Alex Oxlade-Chamberlain against Middlesbrough on 74 minutes as Wenger sought greater creativity from the centre of the pitch.
Cazorla and Coquelin
Arsenal's most popular pairing in central midfield has reaped four wins from five games. That includes Arsenal's 3-0 win over Chelsea, when Coquelin was forced off with an injury midway through the first half with the score at 2-0, and the Gunners' win over Southampton, when Cazorla converted a 90th-minute penalty.
Wenger trusted Cazorla and Coquelin against Paris St-Germain in the Champions League, and was rewarded with a 1-1 draw, while the pair also started together in wins over Hull and Ludogorets, where Cazorla registered an assist.
Xhaka and Cazorla
Arsenal's second most popular pairing is between Xhaka and Cazorla. The Swiss-Spanish combination has returned four wins from four starts, including away victories at Watford and Burnley in the Premier League.
The duo also started together in the 2-0 Champions League win over Basel, while Xhaka was sent off 70 minutes into the 3-2 win over Swansea.
It's worth noting that Xhaka replaced the injured Coquelin 32 minutes into Arsenal's 3-0 win over Chelsea, and played the remainder of the match alongside Cazorla.
Elneny and Xhaka
Elneny and Xhaka have been paired together just once this season. Xhaka opened the scoring in a comfortable 4-0 EFL Cup win over Nottingham Forest.
Coquelin and Xhaka
Coquelin and Xhaka were paired together for Arsenal's 0-0 draw with Leicester in August - with Cazorla taking up a No10 role ahead of them.
It was an impressive defensive display from the pair, before Xhaka's 73rd minute substitution for Jack Wilshere. Coquelin recorded a team-high five tackles and five interceptions, while Xhaka regained possession (nine) more times than any of his colleagues.
Elneny and Cazorla
Arsene Wenger is yet to pair Elneny and Cazorla in any game this season.
Other options
One other option open to Wenger is to field more than two of his central midfielders at once. He did that against Leicester, with Cazorla as a No10, but he has also stated previously that Elneny can play further up the pitch, too.
Wenger has also played Alex Oxlade-Chamberlain in the centre, with the England international taking up that position late on against Middlesbrough as Arsenal searched for a late winner, while currently injured Aaron Ramsey is another option.
Conclusion
Given Arsenal's results with Cazorla in the team so far this season, and the goals, assists and creativity he brings to the team, the Spaniard - when fit - will surely be one of the first names on Wenger's team sheet. The manager even had words of praise for his absent star on Saturday.
Asked whether Arsenal had missed Cazorla against Middlesbrough, Wenger said: "Of course, you always miss [him]. From deep midfield into the final third, with his pass is always quick and accurate."
The choice, then, is who will partner Cazorla: prolific passer Elneny, tough-tackling Xhaka - who has already shown his goal threat from long range - and chief destroyer Coquelin.
Xhaka, Arsenal's £34m summer signing, appears to be the preferred choice to play alongside Cazorla, and the pair have already started together for four wins - and played a significant role in a fifth against Chelsea - this season. But with Xhaka twice seeing red already this season, his temperament may also come into Wenger's thoughts.
Ultimately, the majority of Premier League clubs will be envious of Wenger's options. He has the luxury of mixing and matching his combinations owing to the strengths and weaknesses of his opponents, while, with the Gunners aiming to compete on four fronts, the ability to rotate in this area is an important asset.
Xhaka and Coquelin have, so far, enjoyed success alongside Cazorla. But Wenger will no doubt need all four of his central midfielders at various stages this season.