MONTMELO, Spain — Just when McLaren had nowhere to go but up, it sunk to a new low when Fernando Alonso's first lap of practice for the Spanish Grand Prix ended in a puff of smoke and a pool of engine fluid on Friday.

White smoke enveloped the two-time Formula One champion when his McLaren spun out of a turn and into the gravel at the start of the morning session at the Circuit Barcelona-Catalunya.

McLaren's team radio told Alonso to "stop the car, stop the car, engine problem" as yellowish liquid dripped from the underside. The drip turned into a gushing pour when a crane lifted the McLaren away from the track.

By then, Alonso was being ferried back to the paddock on the back of a scooter, meekly waving to some of the local fans who came to give the Spaniard a much needed boost.

Alonso apologized to his supporters for the no-go, and put the blame on Honda, the maker of the McLaren's troubled motor.

"What can you do?" Alonso said after the humbling day. "It was a pity for the fans that had come today to see me break down on the first lap."

Alonso slipped away from the track and played some paddle tennis to "keep the body active" while mechanics changed out his car's engine before the afternoon session, when he was the last of the 20 drivers to venture out. He finished with the afternoon's slowest time, more than three seconds behind pacesetter Lewis Hamilton.

"I didn't want to spend the morning on the sofa watching television. I preferred to do some sport, so that if the car was ready I would be, too," Alonso said. "I managed a few laps, with more problems than anything else. But that is what Fridays are for. I believe that on other weekends we have had trouble-free Fridays and Saturdays only to not finish the race on Sunday.

"I have the hope that at this grand prix we had our problems on Friday so that on Saturday and Sunday everything will go well."

Champion in 2005 and 2006, Alonso hasn't added to his 32 victories since winning the Spanish GP in 2013. He hasn't finished a race this season, and his McLaren broke down on the formation lap of the previous Russian GP.

The latest blow comes a day after Alonso issued an ultimatum: Either McLaren gives him a competitive car by October or he will look to change teams or consider leaving F1. Alonso has already decided to try his luck at the Indianapolis 500 instead of the Monaco GP this month.

The rest of the practice saw Mercedes register the top two times — with Ferrari's and Red Bull's combined four cars less than a second behind — under sunny skies in northeastern Spain following Thursday's showers.

Sporting a new funky nose to its Silver Arrows, Hamilton and Valtteri Bottas led both the morning and afternoon sessions. Hamilton lowered his own best lap time after lunch, with Bottas only 0.090 seconds slower.

Ferrari pair Kimi Raikkonen and Sebastian Vettel clocked the third and fourth fastest times, less than half a second off Hamilton's pace.

"There is the opportunity this weekend to do a one-two and pull away from the Ferraris," Hamilton said.

Vettel wasn't pleased coming in behind the Mercedes, and put the burden on himself to get more out of his car that has given Mercedes its first real challenge in years. With two wins in four races, Vettel leads the standings with 13 points more than Hamilton.

"I don't know what Mercedes was up to. It looks like it will be between them and us," Vettel said. "But I wasn't happy. I can feel the car is quick. It is a question of getting it right."

Red Bull driver Max Verstappen, who won the race last year at 18 to make history as the youngest winner, and Daniel Ricciardo were next.

After smooth driving early, gusting winds gave drivers trouble in the afternoon. Vettel, Bottas, and Verstappen all skidded off the track and into the gravel near the end of the day.

"A gust of wind could be victory," Hamilton said. "Going from corner to corner the car felt different. It's like juggling balls in the wind."

Practice will resume on Saturday before qualifying for Sunday's race.