Chelsea chief executive Ron Gourlay has hinted that the club's summer spending is not yet complete.
The European champions have already paid out over £60m in transfer fees for Oscar, Eden Hazard and Marko Marin.
Gourlay said: "While we ended with a very strong season, it was clear that there were some areas where we did have to strengthen, so we knew we were always going to have to do that.
"If the right players become available at the right time we will sign them. We've done that and we are still continuing to look at one or two positions and we will see how that develops over the next couple of weeks."
Porto forward Hulk and Wigan Athletic winger Victor Moses are understood to be among the players currently being chased by Chelsea.
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