Jannik Sinner said his lack of energy in a stunning French Open loss was down to a combination of factors, including a long clay court swing, during which he played and won three successive events to arrive as the favourite in Paris.Sinner, who was targeting a maiden French Open title and career grand slam in the absence of his injured rival Carlos Alcaraz, was hampered by illness for a 3-6, 2-6, 7-5, 6-1, 6-1 second-round defeat by Juan Manuel Cerúndolo.After titles in Monte Carlo, Madrid and Rome, and a comfortable victory in his Paris opener, Sinner wilted on Court Philippe Chatrier. “In general, many things came together... I played a lot and I didn’t have a lot of time to recover,” Sinner said in a packed press conference room.“I came here, first match, really good, really solid... even though I finished late, but not crazy late. This morning I didn’t sleep well. When I woke up, I was struggling a bit, but this can happen. Usually in grand slams you have a couple of days where you don’t feel perfect. That was today.”Italy’s Jannik Sinner leaves the court after losing his second round match against Argentina’s Juan Manuel Cerúndolo. Photograph: Stéphane Mahé/ReutersWhile heat and humidity have often tripped up Sinner during big events, the world No 1 said he was at ease in Paris despite the mercury going past 30 degrees Celsius.“Shanghai [in October] was very tough. The humidity was high,” Sinner said about his retirement in the Chinese city. “Australia was very warm [this year], I remember. It’s different when you play on hardcourts, because the heat also comes from underneath,” Sinner explained.“Here, it was warm, but it was OK. It wasn’t like I was dying because of the heat. Today, it was a completely different scenario, but this can happen. It’s tough to accept, of course, because of the position I’ve been in and everything considered, but now I have a lot of time to recover.”Sinner said he would consider skipping grass court tune-up tournaments before his title defence begins at Wimbledon, where the main draw gets underway on 29 June.“I won’t play any tournament on grass before [Wimbledon], most likely,” he added. “I need really some time off to recover completely, also mentally, and then be ready to go again.”This report will update