Alex Oxlade-Chamberlain made the brave decision to swap Arsenal for Liverpool in a £35m deal last summer and it's one he hasn't regretted.

A cruciate ligament injury has kept the 25-year-old out since April and he isn't expected to return until the end of the season, but before that happened all was well.

Oxlade-Chamberlain was patient and worked hard to become a guaranteed starter under Jurgen Klopp and was really blossoming as a central midfielder.

And he's expected to resume that role when he does eventually return because of the speed and directness he provides in the middle of the park.

So why did he leave Arsenal in the first place? The answer is simple: Oxlade-Chamberlain's career was stalling somewhat and he needed a fresh start.

"It was a really hard decision," he said on his move in 2017, per Sky Sports. "It's an honour to play for a club like Arsenal.

"It's an amazing place to play, it was stable, you build relationships, but I felt I had to do it for football reasons to try and better myself."

Oxlade-Chamberlain spent six years at Arsenal but never truly cemented his place in Arsene Wenger's team, for various reasons.

Frequent injuries played a part, while there was always a big fight for places going on at Arsenal due to their sheer amount of attacking options.

However, according to football writer Alan Gernon, there was another strange reason for Oxlade-Chamberlain's lack of minutes.

Gernon claims in his new book The Transfer Market: The Inside Stories that a clause in the Ox's contract meant every time he played 20 minutes for Arsenal, they owed Southampton £10,000.

It would certainly explain why Wenger more often than not used Oxlade-Chamberlain as a late substitute, rather than a starter every week.

"Following Alex Oxlade-Chamberlain's move to Arsenal in 2011, Gunners fans became increasingly frustrated with the midfielder's lack of playing time," wrote Gernon.

"He was predominantly used as a substitute, often around the 71-minute mark.

"After his contract details emerged, it all became clear: Arsenal were obliged to pay Southampton £10,000 every time he played 20 minutes or more."

How bizarre. Oxlade-Chamberlain's clause must have been very expensive for Arsenal to maintain over his six-year stay, so it's no wonder Wenger decided to let him go.

It's all worked out for the best, though, with Oxlade-Chamberlain enjoying his time at Liverpool and Arsenal now thriving under Unai Emery.