Aston Villa have agreed a fee in the region of 37.5 million ($47.7 million) with Chelsea for defender Ian Maatsen, a source has confirmed to ESPN.

The 22-year-old made 16 Bundesliga appearances on loan at Borussia Dortmund last season and started every Champions League knockout round game as they reached this month's final at Wembley.

ESPN reported on June 6 that Dortmund wanted to make the move permanent but were reluctant to activate a 35 million ($44.5 million) release clause specific to them to because of what they believed was a high valuation.

Villa have moved quickly to exploit that uncertainty by offering an amount above that clause and are now confident of finalising personal terms.

The source added that Villa are willing to offer Maatsen a six-year contract. Negotiations are expected to continue over personal terms in the coming days.

It remains to be seen whether Dortmund match Villa's offer but given they had baulked at the original asking price, a late change of heart is considered unlikely.