Fernando Torres says he never dreamed of reaching the level he did under Rafael Benitez at Liverpool.
Benitez signed Torres for the Premier League side for a club-record fee in the region of £20 million in 2007, plucking him from boyhood club Atletico Madrid.
The striker went on to score 81 goals in 142 appearances for Liverpool, but a series of hamstring and knee injuries led to a loss of form and he has struggled to hit those heights in subsequent spells at Chelsea and AC Milan.
Torres admits he did not believe he was capable of what he achieved under Benitez, but also thanked Diego Simeone for bringing him back to the Vicente Calderon.
"They have been very important people for me in different times. With Benitez I reached a level I perhaps never dreamed of," he told Cadena Cope.
"With Simeone I have had the opportunity to return to my club and relive very emotional moments, and I think the best is still to come."
After a barren spell stretching back to September, Torres scored his 100th goal for Atletico in the 3-1 win over Eibar on February 6.
Although his future at the club remains uncertain, the 31-year-old has no doubt he wants to remain.
"My future is to win here, at Atleti. It's something I have not done yet," added Torres.
"At the moment I have the good fortune to play where I want. I do not know until when, but I want to enjoy every game.
"I am aware that my performances have to be better."