The 2000 Serie A champions had sold Juan Sebastien Veron and Pavel Nedved and saw Mendieta as the man to rebuild their midfield around.
Things did not quite work out and the player struggled to adapt to the Italian game.
He was booed by the fans as Lazio were embarrassingly dumped out Europe in the opening stage of the Champions League.
Their domestic form was also alarming and Dino Zoff, the man who had brought Mendieta to Rome, was replaced by Alberto Zaccheroni.
One of his first moves was to drop the 28-year-old.
"I knew it was going to be difficult in Italy but to be honest I didn't think things would work out this way," he said in February.
"Things have been very difficult for me. When your team isn't playing well it reflects on the players and I have suffered."
Mendieta described his first year in Italian football as "shocking".
He made just 12 league starts as Lazio finished fifth in the table - 18 points behind Juventus.
His lack of first-team action even saw him lose his place in the Spanish squad.
While Mendieta's unhappiness reached an all-time low, Valencia prospered in his absence, winning the Spanish title by seven points.
Mendieta's whereabouts next season is still uncertain.
He has been linked with moves to Manchester United - in a swap deal with the equally out-of-sorts Veron - and Athletic Bilbao were said to be keen on taking him back to Spain on loan.
Rumours of a move to Barcelona and Real persist and the unsettled Mendieta appears keen for the comfort of a move back to Spain.