It's fair to say that most people would agree that there is no real downside to having a goalkeeper as good as Petr Cech at your club, but perhaps Thibaut Courtois is one person who would disagree.
The Belgian is one of the most highly rated young goalkeepers in Europe, and already has a Europa League and a Super Cup to his name, as well as an internet craze devoted to replicating his saves in odd locations. However he is unlikely to displace Petr Cech from the Chelsea line up any time soon as the Czech player is still only 30, and as a result he might be keen to look elsewhere.
An indication this is indeed the case could be Chelsea's reported interest in Birmingham's Jack Butland. The young English keeper could be bought for only £3.5 million due to his side's financial trouble, and he would be a better back up option to Cech that Ross Turnbull has proved in recent weeks.
Everton and Liverpool have been long term admirers of Butland, but should Chelsea enter the race, it's likely that they would be able to turn the youngster's head given their greater spending power. Whether Liverpool and Everton could compete by offering a better chance of first team football is unknown, and a lot would depend on Butland's own views on the matter. Chelsea could offer a lucrative contract and the long term chance to replace Cech in a side competing for the top honours, which would be tricky for anyone to resist.
As for Courtois, he will have plenty of options, and Barcelona might even be looking at bringing him in to replace Victor Valdes in the summer. Chelsea perhaps didn't expect him to develop so quickly, but it’s clear they are now going to struggle to keep a player who could be playing Champions League football elsewhere. Butland might have the same view of warming Chelsea's bench, but could be tempted if Chelsea blow the competition out of the water with their offer.