This time Formula One's prankster-in-chief is not joking.

Gerhard Berger, the man whose famous japes included putting frogs in Ayrton Senna's bed, called time on a two-decade career this weekend after the last European race of the season at Monza.

The Austrian, who won 10 grands prix as a driver, ended a five-year spell as a BMW motorsport boss to spend more time with his children and keep a closer eye on the family haulage business.

"It's very simple. I'm just a bit tired. Maybe I'm going to miss it terribly or maybe not, I have no idea," Berger told Reuters at the BMW motorhome in the Monza Paddock.

But one thing is for certain. Others will miss him.

"We had a lot of fun thanks to Gerhard and his mad sense of humour," F1 supremo Bernie Ecclestone told reporters.

"It's good to remember all those wonderful practical jokes he played on all of us."

Like the time Berger was flying over Monza with his great friend and one-time McLaren team mate, the late Ayrton Senna, and flung open the helicopter door, sending the Brazilian's briefcase tumbling into the Italian countryside.

"It fell somewhere near the course but we found it again.," Berger, 44, recalled with a cheeky grin.

Senna was his victim of choice, falling foul of another prank when Berger stuffed frogs into his bed in an Australian hotel room.

"Actually they weren't frogs, they were bigger, more like toads. In Australia they have this kind of stuff. I thought he liked animals but clearly not," Berger explained.

SERIOUS SIDE

Joking aside, Berger can look back on an illustrious sporting career -- both in and out of the car.

Behind the wheel he clocked up a whopping 210 grands prix -- second only to Riccardo Patrese. More recently he led BMW's successful return to the sport after a 12-year absence.

Berger made his debut in 1984 and it was no coincidence that he said farewell at Monza.

It was on Formula One's oldest circuit, driving for BMW-powered ATS in his second race, that he made a name for himself, climbing from 20th on the grid to sixth at the chequered flag.

In 1986, the Italian track provided the stage for his first podium finish when he finished third for Benetton.

Berger says one of his most treasured F1 memories is his Monza win for Ferrari in front of the home crowd a month after the death of the company's founder Enzo Ferrari.

"To win the Grand Prix here in 1988 with Ferrari is something I like to remember," he said.

Fifteen years later, he can scent victory again, this time with BMW who are in pole position for their first constructors' title with Williams.

After Sunday's Italian Grand Prix, Williams lead the standings by 141 points to Ferrari's 137.

RESISTING TEMPTATION

Berger might have been tempted to postpone his retirement had BMW decided to build their own car but when the German company signed up with Williams until 2009 he decided it was time to go.

"It would have been very challenging and I don't know if I would have had the balls to say no. But I'm very happy that it turned out this way because I'd really like to have a bit of a break," said Berger.

Williams boss Frank Williams wishes him well.

"When he was a driver we were in negotiations several times. Basically it always broke down because he wanted too much money. I have to admit I enjoyed having him for a couple of years now -- for free," he said.

As Williams and Ferrari battle it out in the last two races of the season, Berger's loyalties are divided.

"I don't make a secret out of it. I am a big Ferrari fan, I love them, they were my family for a long time," he said.

While Monza was supposed to have been his swansong, Berger might not be able to resist a jaunt to Japan for the season's climax.

"If BMW and Williams really have a chance to win the championship, I would love to be there," he said.

F1's retiring rogue may yet have the last laugh.

Formula One 2003 - The complete coverage