Chelsea technical director Michael Emenalo was at the La Rosaleda stadium on 11 April during the La Liga game between Malaga and Atletico Madrid to scout the developments of Koke, reports in Spain claim.
The 23-year-old versatile midfielder attracted the attention of a number of big European clubs after becoming a crucial asset for manager Diego Simeone during last season's excellent march to the La Liga title and the Champions League final.
The Spain international was linked with a move to Manchester United and Chelsea during the summer of 2014, while Barcelona were said to have earmarked him as the long-term replacement of Xavi Hernandez.
However, Koke decided to commit his future to the Vicente Calderon until 2019 by signing a new lucrative contract that increased his release clause to €60m (£43m, $65m).
But, according to Spanish newspaper AS, Chelsea boss Mourinho has the Atletico Madrid midfielder as one of his top targets for next season and is ready to renew his club's efforts to secure his services in the summer.
AS claimed Emenalo travelled to the capital of the Costa del Sol earlier in April to see the midfielder in action during the 2-2 draw between Simeone's side and Malaga.
Having provided 11 La Liga assists and four in the Champions League this season, the Spaniard played the 90 minutes of the game but could not added any more to his impressive tally.
But AS claims the Portuguese boss is a big admirer of the Spaniard and would like to reunite him with former Atletico Madrid teammates Diego Costa and Thibaut Courtois at Stamford Bridge.
The report says Mourinho would be open to include Filipe Luis as part of the deal to secure his services. However, the Spanish newspaper says the only way to lure him out of the Vicente Calderon is to match his €60m release clause.
Meanwhile, AS points out Manchester City sporting director Txiki Begiristain also went to watch Koko earlier this season, during the Champions League game at Juventus.