#1 Arjen Robben
Chelsea signed Dutch winger Arjen Robben in 2004 for a fee of £12 million from PSV Eindhoven. He was just 20 years of age at that time and proved to be one of Abramovich’s best investments.
Despite being thronged with injuries, he proved to be crucial for Chelsea as they secured a second successive Premier League title. In the three seasons at Stamford Bridge, he scored 15 goals in 67 League appearances and ended his Chelsea career with an FA Cup victory over Manchester United in 2007.
Real Madrid duly bought the talented winger and since then the Dutchman has only got better with age. He took the Dutch national side to the World Cup final in 2010 and has won many trophies with Bayern Munich. Chelsea fans still rue as to why Abramovich let him leave just when he was about to hit peak form.