Sevilla director Monchi has claimed Chelsea hesitated to complete the signing of centre-back Jules Kounde, allowing Barcelona to sneak in and get a deal done.
Chelsea agreed both a transfer fee and personal terms with Kounde and had been expected to get a deal done earlier this month, only for Barcelona to eventually match their offer and convince the Frenchman to make the move.
"On Thursday, we reached a verbal agreement with Chelsea and the player had also agreed personal terms with the English side, but everything stopped over the weekend," Monchi told SFC Radio.
"In that tug of war with Chelsea, Mateu Alemany (Barcelona sporting director) contacted me on Monday. After working on amounts, we reached an agreement, achieving the most important sale in the club's history."
Monchi added: "Kounde agreed on the sale to Chelsea, there was an agreement with the player. At the club, they hesitated and said they wanted to wait. That wait continued and Barça appeared. It is true that Chelsea later wanted to return, but Barça's offer at the end was better.
"There were several suitors at the beginning of the summer, but only Chelsea and Barcelona remained at the end. Chelsea began to have doubts, not about the player but the way to approach the market for defensive reinforcements. Their offer was good but they decided to stop.
"Alemany voiced his interest to us, we asked him for an offer and one arrived that is lower than we had in mind. After working on it with a significant effort from Barcelona, we reached a significant amount."
Monchi went on to admit that Kounde was expected to join Chelsea earlier in the week, but Barcelona eventually swooped in and changed everything.
"The player, I repeat, was sold to Chelsea on Thursday, with an agreement from all parties," Monchi said. "But sometimes, new situations arise.
"There was movement at Chelsea that made them doubt whether the profile they needed was Kounde's. I do want to emphasise that Barcelona's was the best firm offer."