Porsche is facing a "disadvantage" in this year's Le Mans 24 Hours GTE Pro battle because of a lack of testing at the Circuit de la Sarthe with the new 911 RSR-19, says Richard Lietz.
Of the three manufacturers in GTE Pro this year, Porsche is the only one running with a new car, having introduced the RSR-19 at the start of the 2019-20 FIA World Endurance Championship season last September at Silverstone.
Aston Martin meanwhile goes into its third edition of Le Mans with the Vantage GTE, and Ferrari's 488 GTE is heading into its fifth outing in the French classic.
After the coronavirus pandemic caused this year's race to be rescheduled and the traditional pre-event test day to be cancelled, Lietz - who shares the #91 Porsche with Gianmaria Bruni and Frederic Makowiecki - says Porsche could be on the back foot initially.
"I think we have done everything to reduce this disadvantage as much as possible," said Lietz.
"We tested at Monza, we done a lot of test days, we've been in the simulator. We know our car with the low-downforce package, that's for sure.
"But you can't prepare for Le Mans anywhere other than Le Mans, because you only have here these high kerbs, and not in Monza or Le Castellet or Aragon, where there are long straights where you reach similar top speeds."
Teams will get 10 hours of track running at La Sarthe on Thursday - including two daylight practice sessions, a 45-minute qualifying session and a further four hours of night practice - prior to a one-hour FP4 session and a half hour 'hyperpole' session on Friday.
Fellow Porsche driver Laurens Vanthoor countered that any disadvantage would be counter-balanced by the greater potential of the new car, which scored its second race win in the most recent round of the WEC at Spa last month.
"We're missing a little bit of knowledge with the Le Mans aero kit and so on, but I don't see it as a problem, because I think Porsche is one of the best at preparing for this race," said Vanthoor, who shares the #92 car with Kevin Estre and Michael Christensen.
"There will be some question marks to solve, but I don't see it as costing us a chance at the race at all. I think this car is better than the 2017 car, has more potential."
LMP2 favourite faces similar concerns
Filipe Albuquerque said United Autosports is going into Le Mans "blind" because it also hasn't had chance to test its ORECA LMP2 car at the circuit.
The squad co-founded by Zak Brown is unbeaten in LMP2 competition in 2020, having won all three European Le Mans Series races of the season so far and the last three rounds of the WEC, stretching back to last November's Bahrain race.
However, this weekend will mark the first time United is going into Le Mans using the benchmark ORECA 07 chassis, having only made the switch from its previous Ligier JS P217 at the start of the 2019-20 WEC season.
Albuquerque, who will share United's lead entry with regular WEC teammates Phil Hanson and Paul di Resta, thinks this could put the team at a disadvantage compared to its main rivals who are going into the race with more continuity.
"There is one point not playing into our favour which is going to Le Mans with no test day," said Albuquerque.
"We are going into it blind, without knowing how the car reacts there.
"Normally we would have the test day and then time to analyse it before we go again. This time it's going to be trickier.
"We need to adapt fast to the ORECA, especially for me it's been four years in a row with Ligier and now we're going to have completely different aero for the Porsche Curves. I expect this car to be very different."