Tournament host Sergio Garcia admitted he was suffering from mental fatigue after struggling to an opening 74 in the Open de Espana at Valderrama.
Garcia, who won the last European Tour event to be staged at the former Ryder Cup venue in 2011, was one under par after eight holes but came home in 39 to finish three over par, eight shots behind first-round leader Alexander Levy.
And it could have been even worse for the world No 16, who holed from 30 feet for par after finding water on the fourth and from 20 feet on the last after a poor drive.
"I'm in a difficult moment of the season," said Garcia, who was three off the lead after an opening 69 in the Masters last week but shot 81 in the third round and eventually finished 34th at Augusta National.
"I'm a little bit mentally tired I guess, which is disappointing for me to come here to the Open de Espana and feel like I am not maybe as strong mentally as I would like to be. I just have to fight hard and get through it. I am going to have a nice break after this which I feel like I need.
"Scheduling-wise, with the Olympics and everything you have to find a way of getting your numbers [of tournaments] up in America and Europe earlier on in the year. Unfortunately you have to go through stretches where I would not like to play as much but I have to."
Garcia rates Valderrama as his favourite course in the world, adding: "It's great to see a golf course that is only 6,900 yards that plays so tough, even with almost perfect conditions like we had today.
"There are chances but there's always danger lurking. Even on holes where you have chances, you still have to hit great shots. For example on 17 I made birdie and almost an eagle, but it was still a three iron over the water and I just carried it by a couple of yards."
Frenchman Levy, who was second in the Perth International earlier this season, carded seven birdies and two bogeys in a five-under-par 66.
"It's a very tough golf course but I like when it's tough because it's not a putting contest," Levy said. "You need to play well from tee to green and it's the way I like to play a golf course, that's for sure."
Levy is one shot ahead of Welshman Stuart Manley, English duo Andrew Johnston and James Morrison and Spaniard Alejandro Canizares.
Defending champion Morrison carded five birdies and one bogey in the tougher afternoon conditions despite coming into the event after a six-week break.
"I played great," he said. "It's a different experience coming back as defending champion but I am enjoying every moment. When I play bad golf it's because I start having expectations, and at the end of last year came good golf and expectations and world rankings and I let my ego get in the way of the process.
"The last six weeks I put the clubs away and had some good family time, and missed cut or made cut it's going to be a good week."
Having started on the back nine, Manley was level par at the turn before reeling off five birdies in the next six holes, with a bogey on the eighth denying the 37-year-old a share of the lead.
"Any time you break par on this course you have done really well," said Manley, who regained his card via the qualifying school last November. "I would have taken 71 at the start of the day because in the practice rounds I thought it was really tough, so I'm delighted with 67."
Two-time major winner Martin Kaymer of Germany is three shots off the pace after a 69, but in-form Spaniard Rafa Cabrera Bello could only match Garcia's 74.