Having already secured attacking midfielders Eden Hazard and Marko Marin this summer, Chelsea continue to be active in trying to strengthen their squad for next season's challenges. Their top priority now appears to be recruiting a top class central midfielder.

The Blues came close to securing Luka Modric last summer, but had three offers rejected by Tottenham. Modric, though, looks to be firmly back on the agenda this summer. Chelsea will face some serious competition if they are to finally bring the playmaker to Stamford Bridge, with Real Madrid and Manchester United also said be strongly pursuing the 26 year old.

Spanish journalist Guillem Balague has reported in AS that Real's offer has encountered difficulties with their midfielder Nuri Sahin unwilling to move the other way in part exchange.

While this should theoretically boost Chelsea's chances, Spurs appear less than eager to sell their prized asset to a fellow Premier League club. The Blues' odds may not be helped, either, by the appointment of former Chelsea boss Andre Villas-Boas at White Hart Lane.

With a deal for Modric appearing complicated, Chelsea could instead turn their attentions to Portuguese midfielder Joao Moutinho. The Porto star appears to be the Modric alternative for more than just Chelsea, with the Sun reporting that both Manchester United and Tottenham are also interested in the 25 year old.

Moutinho played a key role in Portugal's run to the semifinals of Euro 2012 and has also helped Porto to back-to-back Portuguese Liga titles in the past two seasons. According to the Sun, Manchester United are already readying a £25 million offer.

Just how strong an interest Chelsea have in Moutinho is unclear. There may be more than a hint of publications currently merely attaching Chelsea's name to speculation over every big name midfielder.

Another case in point may be Benfica's Axel Witsel. The all-round midfielder is said to have been on the radar of many of Europe's big guns for several months after impressing as his side reached the quarterfinals of the Champions League last season.

And, according to TalkSport, Benfica may now be ready to listen to offers for the 23 year old. Although he only joined the Lisbon giants from Standard Liege last summer, it is thought that an offer of £20 million may be sufficient to secure his services.

Unsurprisingly, it is reported that Manchester United and Chelsea are interested in the Belgium international's signature.

More concrete speculation appears to come in the form of Chelsea's interest in Southampton left-back Luke Shaw. The Guardian reports that Chelsea will bid £4 million this week for the highly-rated England Under-17 international, who turns 17 on July 12.

Despite only making one first-team appearance for the newly-promoted Premier League side, Shaw is thought to have displayed enough potential to also interest Manchester City and Arsenal. In recent years Southampton have developed some of the best young talent around, having also produced Gareth Bale, Alex Oxlade-Chamberlain and Theo Walcott.

Although they already have Ashley Cole and Ryan Bertrand on their books, Chelsea appear to be in prime position for Shaw's signature.