Speaking ahead of Chelsea's Super Cup clash with Liverpool, the Blues boss picked out three of the finest players he came up against.
"Can I give you two answers? It'll actually be three," the Chelsea legend told UEFA's official website.
"The first one is Messi because he was the most incredible player -- it was like you were playing against someone who's not on the same level as all of us.
"The two players I always remember having the hardest time against were Xavi and Iniesta at Barcelona. They just played football around you, and you didn't get near them.
"It was football that wasn't normal to me; it was different from anything else I came up against."
Lampard, 41, played against the Barcelona captain in 2009 and in the Champions League semi-finals back in 2012.
But the former Chelsea midfielder had the last laugh over Messi in 2012 as the Blues knocked the Spanish side out of the competition on route to winning the Champions League.
Lampard's Chelsea were thrashed 4-0 in their opening Premier League match against Manchester United on Sunday.
But the former England international is expecting his side to bounce back against Liverpool in the Super Cup clash in Istanbul.
Lampard has also revealed that he wants to leave his mark at Stamford Bridge as Chelsea boss and capture silverware with his side.
"It is a defining thing in my life, because I took Chelsea home with me the minute I joined the club," he explained.
"When I look back, I'm delighted at what I managed to achieve, or what we did as a group, except for that we should have won more Premier League titles.
"I feel for this club deeply. Hence why I want to do so well here.
"Of course, I want to do well for myself, I want to improve myself but at the same time, I want this club to be where it belongs."
Liverpool star Sadio Mane also admitted ahead of the Super Cup clash that Messi should win the Ballon d'Or ahead of himself and Virgil van Dijk.
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