The 27-year-old has kept four clean sheets in seven matches while Mendy was engaged at the Africa Cup of Nations, including Wednesday's Club World Cup semifinal win over Al-Hilal in Abu Dhabi.
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After winning the AFCON with Senegal, Mendy joined up with his club teammates at their Ritz Carlton hotel base on Wednesday.
It is understood that Chelsea head coach Thomas Tuchel is seriously considering replacing Kepa with Mendy for Saturday's final against Palmeiras despite the club's coaching staff acknowledging key improvements the Spaniard has made in his game over recent months.
Kepa is said to have responded well to encouragement to alter his goalkeeping style, specifically becoming more aggressive and avoiding the temptation to retreat to his goal-line too often during matches.
However, Mendy has enjoyed a stellar year having played a vital role in last season's Champions League success -- later named UEFA Goalkeeper of the Year -- and opportunities for Kepa are expected to be restricted now he is available for selection.
Kepa has been praised behind the scenes for his work ethic and commitment to improve but the probable lack of game-time is likely to lead to renewed interest from abroad with sources suggesting to ESPN Chelsea would be willing to listen to offers for the Spaniard.
Kepa joined Chelsea in 2018 from Athletic Club for £71.6 million, a fee which remains a world-record for a goalkeeper. There is an acknowledgment that Chelsea will have to accept a loss but he still has three years remaining on his Chelsea contract, worth around £150,000-a-week.
Meanwhile, Tuchel will take a further COVID-19 test on Friday as he plots a last-minute dash to the Middle East to make it in time for Saturday's final. The Chelsea boss missed Wednesday's game after testing positive shortly before last weekend's FA Cup fourth round win over Plymouth Argyle.