Ye went fastest half an hour into the first 90-minute session with a 1m31.347s aboard the customer AF Corse-run 499P Le Mans Hypercar to push the best of the works Ferraris with Anthony Fuoco at the wheel down to second position.
Fuoco ended up on 31.503s, which gave him a margin of nearly half a second over the first non-Ferrari, the Peugeot 9X8 2024 LMH driven by Mikkel Jensen that finished on 1m31.964s.
Lamborghini took fourth place with Mirko Bortolotti aboard the solo Iron Lynx Lamborghini SC63 LMDh.
The Italian's 1m32.015s briefly put him at the top of the times during the opening minutes of the first practice period.
The second factory Ferrari 499P took fifth place on a 1m32.065s from Antonio Giovinazzi.
A late improvement from Julien Andlauer propelled the Proton Competition team's customer Porsche 963 LMDh into sixth position ahead of the two factory cars.
The Frenchman's 1m32.253s gave him a margin of just eight thousandths over Matt Campbell's 1m32.261s in the first of the Penske Porsche Motorsport entries.
Kevin Estre was less than two tenths behind in eighth in the second PPM 963 with a best lap of 1m32.426s.
The pair of Toyota GR010 HYBRID LMHs ended up ninth and 10th in the times, a 1m32.505s from Nyck de Vries giving him a margin of two tenths over Sebastien Buemi's 1m32.739s in the sister car.
Callum Ilott ended up just outside the top 10 in the Jota Porsche that took the runner-up spot in last month's Qatar 1812 km WEC season-opener.
He narrowly edged out Rene Rast in the best of the WRT BMW M Hybrid LMDhs.
Matthieu Vaxiviere ended up 15th in the best of the Alpine A424 LMDs with a time just under two seconds off the pace.
The TF Sport Chevrolet squad led the way in LMGT3 with its pair of Corvette Z06.R GT3s.
Daniel Juncadella's 1m42.113s set early in the session gave him a clear margin over team-mate Charlie Eastwood in the sister car, which lapped on 1m42.719s.
Davide Rigon was third in class in the fastest of the AF Corse Ferrari 296 GT3s with a 1m42.971s, which was just over a hundredth up on the best of the WRT BMW M4 GT3s in which Maxime Martin posted a 1m42.988s.
Alessio Rovera and Augusto Farfus took fifth and sixth respectively in the second cars from AF Corse and WRT.
Porsche took seventh position with the Manthey-run 911 GT3 R driven by Morris Schuring.
Aston Martin, Lexus and McLaren filled out the top 10 in LMGT3.
Second practice for Sunday's Imola 6 Hours begins at 17:15 local time.
