Chelsea are losing patience with Diego Costa and will consider selling him this summer.

The striker has struggled for form since Tianjin Quanjian offered a contract worth in excess of £570,000-a-week in January and has scored just three Premier League goals in 2017.

Despite the Chinese Super League side offering £80million, Chelsea made it clear Costa was not for sale at the time because he has been a key part of the quest to win the Double but Tianjin plan another bid during the next transfer window while his former club, Atletico Madrid, remain keen.

The Spain international has started all but two of the club’s League games this term but this is the second time in three years his performances have tailed off significantly in the second half of the campaign.

The 28-year-old has two years left on his contract and while preliminary talks took place over an extension in February, the club are having second thoughts, especially as he wants a significant increase on his £150,000-a-week salary.

Standard Sport revealed in January Chelsea were already planning a new move for Romelu Lukaku or Alvaro Morata after missing out last summer.

Lukaku, who played just one League game for the club between 2011-14 before moving to Everton for £28m, is now first choice, although the Blues are looking to bring two centre forwards in should Costa depart and have added Arsenal’s Alexis Sanchez to their wish-list.

As first reported by this paper a year ago, Lukaku has made a return to Stamford Bridge his priority because he feels he has ‘unfinished business’ there and that remains the case.

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The 23-year-old has refused a new contract at Goodison Park and it has been reported Everton will demand £100m for the Premier League’s top scorer, who has 24 goals.

The relationship between the clubs soured after Chelsea had four bids rejected for defender John Stones, who is now at Manchester City, in 2015.

But Chelsea’s bargaining position has been strengthened with Everton now interested in their Academy starlet Tammy Abraham, who has impressed on loan at Bristol City.

The 19-year-old forward has 22 goals in the Championship, making him joint-second in the scoring charts in that division.

Everton are keen to invest in young English talent, and have identified Abraham as one of the best outside the Premier League. In January, they agreed a deal worth a possible £11m to sign Ademola Lookman from League One club Charlton.

Abraham is thought to be aware of Everton’s attention, and said recently he did not know which club he would be playing for next season. “It is something that has played on my mind,” he said. “I need to get through this season first and finish on a high. It would be a dream to play in the Premier League.”

At this stage, Chelsea are unwilling to sell Abraham. It is believed they turned down an offer of £10m from a top-flight club in January, even though Abraham has never played at that level.

Abraham is highly-regarded by Chelsea coach Antonio Conte and will be considered for a squad role next term. However, it is more likely he will be loaned out to a top-flight club or high-ranking Championship side in order to continue his development, on the condition of regular first-team football.

Chelsea have been willing to lease promising players to domestic rivals in the past, with Lukaku himself having spells at both West Brom and Everton before moving to Goodison Park on a permanent basis.

Chelsea are confident Lukaku is keen to return to Stamford Bridge and Everton’s interest in Abraham may strengthen their hand.