The current Russia boss has worked with legendary figures as Alessandro Del Piero, Raul, Marco van Basten, Francesco Totti and Ronaldo during his coaching career and he feels the Brazilian was the pick of an illustrious bunch.
"Technically the best? Absolutely, Ronaldo - and not Cristiano," Capello said via Uefa's official Twitter account when questioned about the best striker he's worked with.
"[Marco] Van Basten was very good, but I think when Ronaldo was at his fittest, he was the best."
The 67-year-old then moved on to discuss who he thinks are the best players of all time and singled out former greats such as Diego Maradona and Pele, as well as current Barcelona star Lionel Messi.
"It goes in three different eras I think. At the start, between 1970 and 1975, this player was absolutely Pele. Then it moved to Maradona. Now? Messi."
Capello also had his say on this year's Champions League favourites and he thinks Arsenal could spring a surprise this term.
"At the start of the Champions League, before the first round of games, I thought Real Madrid, Bayern Munich and Barcelona can win it. From England, I like Arsenal," the former Three Lions boss added.