The World Cup is not only football's biggest tournament, but it also serves as a shop window for players to impress onlooking clubs.
Jose Mourinho's first season back at Chelsea ended in disappointment as the Blues failed to land a trophy, but fans can be confident that they will mount a title challenge next season having come so close this time around. Mourinho will now be planning a summer of spending in order to get Chelsea over the finish line, and some World Cup stars may be of interest.
With central midfielders and strikers needed at Stamford Bridge, you can be sure that Mourinho will be bringing some new faces in to fill those holes, whilst depth could also be added to the defence. With that in mind, here are five stars playing in Group A at this summer's World Cup that could fit the bill.
Whilst he's been in and out of the Tottenham side this season, Paulinho is a favourite of Brazil boss Luiz Felipe Scolari, and is expected to start alongside Luiz Gustavo in holding midfield this summer. A £17m capture for Spurs last summer, Paulinho is reportedly unhappy at White Hart Lane and will seek a summer transfer, and Mourinho has been strongly linked with tying up a £20m move to partner the Brazilian with Nemanja Matic at Stamford Bridge. With sporadic appearances under Tim Sherwood, playing on the biggest stage will show Chelsea whether he's ready for the step up or not.
The Zenit St. Petersburg star is expected to start out on the right hand side for Scolari's men, where he will no doubt be cutting inside on to his devastating left foot. The former Porto forward is believed to be interested in a move to England at the end of the season, and whilst Zenit have reportedly slapped a £40m price tag on his head, Chelsea are still interested in bringing him to West London in a bid to boost their attacking firepower - which ultimately let them down at crucial points this season.
Mario Mandzukic, Croatia
Another player who could boost their attack is Bayern forward Mandzukic, whose 48 goals in 88 games for the Bundesliga giants have seen him becoming one of the most feared strikers in football. The Croatian hitman is under threat though at the Allianz Arena, as the impending arrival of Robert Lewandowski means he may struggle for first team football, and Chelsea are believed to be one of the front runners for his signature this summer, with a rumoured fee of around £25m on the former Wolfsburg man's head.
Ivan Rakitic, Croatia
With their interest in Paulinho fairly well known, Mourinho is acknowledging that Chelsea need to get better in central midfield. John Obi Mikel has been linked with a summer move away from Stamford Bridge whilst Ramires has had a disappointing season. Whilst not a true box-to-box player like Paulinho is, Rakitic is a technically gifted midfielder who can score goals from distance and from set pieces, and has attracted interest from the Blues of late - but would cost around £33m to prise away from Sevilla.
Hector Moreno, Mexico
The leading star of the Mexico defence, Moreno has been a dependable figure for both country and club, where he plays for Espanyol in La Liga. The 26-year-old was linked with a move to Stamford Bridge last summer after impressing Mourinho in Spain, but no deal was done at the time. Now, David Luiz could be heading for the exit, and whilst Kurt Zouma will join the club, Chelsea may need more depth behind the ageing John Terry, and impressive displays at the World Cup could convince Mourinho that Moreno is the man to come in.