Federer leads their head-to-heads 14-11 overall, but momentum has more recently been with the Serb - top seed at Roland Garros.
And after his battle with Tsonga, Djokovic believes he knows what to expect from his foe as he bids to become only the third man to hold all four Grand Slam titles at the same time.
"We all know his quality and can always expect him to perform his best at this stage of the tournament," he said.
"We both played tough matches in the last two rounds. Now we're going to have two days off and expect an exciting semi-final.
"I think for me it's crucial to be very focused and aggressive from the first moment, because that's something that you can always expect Roger to have, you know, that control over the opponent from the start.
"Now there is no real favourite for that match. It's semi-finals, so everything is open."
Djokovic lost in four sets to Federer in last year's French Open semi-finals, but that was his only defeat in their last six encounters.
Federer, bidding for a record 17th Grand Slam title here, sounded equally even-minded after his victory over Del Potro, which saw the Swiss star struggle for two sets before the tall Argentinian wilted physically.
"I know that I have to reach a level of 10 to play against him. So that's all I can say. We'll see," he said.
"We'll see how fit he is. I know I have to play a great match."
Both men know that the winner in Friday's semi-finals will likely face an even greater challenge in Sunday's final should, as expected, six-times winner Rafael Nadal make it through.
Nadal has roared into the quarter-finals for the loss of a meagre 19 games and has yet to drop a set.
Neither Djokovic nor Federer has ever beaten Nadal at Roland Garros, with the Spaniard now having a career record here of 49 wins and just the one loss, to Robin Söderling of Sweden in the fourth round in 2009.
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