The potential signing of Hulk would take Chelsea's summer spending to around the £100-million mark. Reuters

Chelsea have already been successful in the transfer market this summer to the tune of over £60 million, but speculation suggest that there remains four targets firmly on the club's radar before the close of the transfer window.

Eden Hazard, Oscar and Marko Marin have been added to a squad that won the Champions League last season, yet there are still key areas in need of strengthening.

Perhaps the priority is to finally solve the club's long-running problems at right-back. With Branislav Ivanovic essentially playing out of position on the right of defense for some time now, the Blues' are eager to recruit a player that can add the quality going forward provided by Ashley Cole on the left. That need has only been intensified with the departure of Jose Bosingwa this summer.

Spaniard Cesar Azpilicueta has long been top of the club's list of targets, but no deal has yet been struck with his club, Marseille.

French publication La Provence claims that a deal will be struck imminently, though, with the 22-year-old's representatives traveling to London to put the final touches on an agreement. The transfer is thought to be worth between €8 million (£6.3m) and €10 million (£7.9m).

The Blues' pursuit of Hulk has gone on even longer than that of Azpilicueta. Speculation has been rife all summer that the Brazilian would be arriving at Stamford Bridge, but Porto's valuation of the player has continued to prove elusive.

However, there could be hope on the horizon with the London Evening Standard claiming that Chelsea believe they can eventually strike a deal for £32 million.

With differing reports claiming Porto's asking price to be anywhere between £40 million and £60 million, it could be some time yet before any deal is done. If the 26-year-old forward is to become a Blue then it is likely that he will have to continue to talk up his desire to leave, as he did recently.

Despite the continued pursuit of Hulk, Chelsea remain keen to add Wigan's Victor Moses. Though both are versatile, each have flourished primarily in a position on the right of the attack.

Chelsea have already had several bids rejected by Wigan for Moses and Latics chairman Dave Whelan has urged Chelsea to pay the asking price-reportedly £9 million-or cease their pursuit of the 21-year-old.

"Chelsea have got to make their mind up-- yes or no--and at present they're messing about a little bit which is unusual for Chelsea because they're up front if they want someone," Whelan told Sky Sports News. "They would usually go and make a bid and get the player.

"With Victor, Chelsea have come in with offers including payments later etc. It's unusual for Chelsea because they're usually a very straightforward club."

"If they come with the fee, we'll sell him. If they don't, we'll keep him.

Chelsea could also be faced with some tough negotiations if they are to secure what looks to be their primary striking target Edinson Cavani.

The Blues are said to view the prolific Uruguayan as the ideal replacement for Didier Drogba. According to the Daily Mail, though, the club is reluctant to meet the 25-year-old's demands for £150,000-a-week wages on top of Napoli's £35 million asking price.

The Mail reports that Chelsea technical director Michael Emenalo has told Cavani's representatives that they will not proceed with negotiations unless his salary requirements are lowered.