Alex Oxlade-Chamberlain admits leaving Arsenal was the hardest decision of his life but the opportunity to work with Jurgen Klopp at Liverpool was one he could not turn down.The England midfielder completed his move to Anfield on deadline day in a deal believed to be worth up to Â£35million after rejecting the chance to join Premier League champions Chelsea.Oxlade-Chamberlain won the FA Cup three times during his six-year spell at Arsenal but felt he had to move on to further his career. "It was the hardest decision I've ever had to make," the 24-year-old told The Times. "I want to thank the Arsenal fans who've always supported me. But I can't apologise for my decision to leave. I want to get more out of myself."I felt the main thing was taking myself out of my comfort zone. That's why Liverpool shouted out for me. "Having been someone on the outside looking in, I couldn't help but notice what the manager (Klopp) is doing here, and wondering what it would be like to play for a character like that. "He's very inspirational, passionate, involved and intense. I felt that was something that could gee me up. "You can see from how the team play how he instils that intensity in the players. I feel like that kick up the backside would be good for me."The manager can take me up to the next level."Oxlade-Chamberlain is in line to make his Liverpool debut at Manchester City in Saturday's lunchtime clash.