Jose Mourinho has told ESPN FC he was "a bit scared" when Radamel Falcao joined Manchester United in the summer of 2014, and the Chelsea coach backed his new striker to regain his scoring touch at Stamford Bridge this season.
Chelsea signed the Colombian striker this month on a season-long loan from Monaco despite Falcao's struggles at Old Trafford, which saw him score just four goals in 29 games last season.
Given Falcao's career record, Mourinho admitted he expected a more prolific return.
"When he went to Man United I have to say I was a bit scared," Mourinho said in an exclusive interview with ESPN FC. "Because he's a predator in the box and a guy who does score goals all the time. He did that in every club in every league, so I was convinced he was going to do that in our league, in England."
Despite the poor scoring results, Mourinho is convinced that Falcao, 29, still has much to offer and does not put down his lack of production to any physical ailments.
"We had a very exhaustive analysis of his condition before we made a decision," Mourinho said. "Our doctor had real work to investigate all of that. He is not, for sure, a physical problem. So if it's not physical, we can make him score goals again."
Falcao is currently with Chelsea on the club's U.S. tour, having played for Colombia at the Copa America earlier this summer. He failed to score in the tournament but, while his recent form has been indifferent, Mourinho hopes his familiarity with Falcao can help the Premier League champions.
"Falcao was in my league when he was in Portugal. We moved to Spain at the same time," Mourinho said. "When I went to Real Madrid, he went to Atletico, so we spent three years in the same league.
"Then I came to England and he came to England too. So I know obviously this player very well."
With Didier Drogba having left Chelsea at the end of last season, Falcao joins his former Atletico Madrid teammate Diego Costa, as well as Loic Remy, as the club's striker options.
Meanwhile, Mourinho has challenged Chelsea to improve in all areas as they embark on their title defence, which begins at home to Swansea on Aug. 8.
In addition to Falcao, Asmir Begovic is the only major signing made by the Stamford Bridge club, and Mourinho is aware that the spending of Chelsea's rivals represents a great challenge.
"The other clubs are going to improve immediately because of the top quality players they bought," the coach said.
"To improve, we have to improve ourselves. I have to be a better coach, they have to be better players, we have to have a better medical department. We must improve by ourselves."
Watch more from ESPN FC's exclusive interview with Jose Mourinho on this website and ESPN FC TV (nightly in the U.S. at 6 p.m. ET on ESPNEWS and WatchESPN). Plus, ESPN FC TV debuts on BT Sport in the UK on Saturday at 8:30 a.m.