MONTMELO, Spain (AP) — Fernando Alonso crashed his McLaren and was taken to the hospital during Formula One preseason testing on Sunday, before Romain Grosjean steered his Lotus to the fastest lap of the week.

Pastor Maldonado had already put Lotus on top of the timesheet on Thursday and Saturday, and Grosjean bettered that by setting the fastest time of the four-day test with a lap of 1 minute, 24.067 seconds.

That was after the session was halted when Alonso went off the track at curve three and slammed the right side of his McLaren into the wall.

McLaren said the former two-time champion was "conscious and spoke with the doctors" before being airlifted by helicopter to a nearby hospital for "precautionary checks." It later said he was unharmed other than a concussion he received during the accident.

"Fernando's accident was just one of those things that happens in testing," McLaren team director Eric Boullier said. "Fortunately, he's fine, but was concussed during the accident, which therefore required an overnight stay in hospital as a precaution."

Alonso's accident comes after a difficult preseason for McLaren in its switch to Honda engines. A faulty seal twice limited Jenson Button's runs earlier this week. Button was scheduled to drive Sunday afternoon, but McLaren called it quits after Alonso's crash.

Nico Rosberg, Red Bull's Daniil Kvyat and Sauber's Felipe Nasr all clocked laps within 1 second of Grosjean.

Rosberg put Mercedes ahead of Ferrari— this time driven by Sebastian Vettel— for the second straight day, after the Italian team had proven faster through the first six days of testing.

"Looking at the times it's of course still not clear where we stand and we're keeping a close eye on the competition. But we're confident that we have a good car at least," Rosberg said. Rosberg, last season's runner-up to the title, was also the day's busiest driver with 131 laps.

Toro Rosso newcomer Carlos Sainz Jr. also hit the wall exiting turn three.

"Strong winds made track conditions very tricky and the car was therefore difficult to drive," Sainz Jr. said. "Even with the wind, things went well, I did several short runs that looked good. Unfortunately, in the afternoon, I made a mistake at turn three, which is not the best place to do that, because the barriers are close at that point."

The third and final set of tests will be at the same track from Feb. 26- March 1 before the season starts in Australia on March 15.