Formula One bosses have warned they will take action against any more bad behaviour after claims that fans shouted racist abuse at Lewis Hamilton.
It's claimed Spanish fans booed and shouted nasty things at Hamilton at the Circuit de Catalunya in Spain.
In the past, Hamilton, 23, hasn't got on very well with his Spanish McLaren team-mate Fernando Alonso.
Some of the crowd painted their faces black and wore T-shirts saying 'Hamilton's family', on Saturday.
Spanish newspapers say track staff had to put up extra barriers because of fears for Hamilton's safety.
They report that banners were taken down and people were moved from the stands above McLaren's garage so nobody could throw anything down.
Track bosses pleaded with fans to behave properly, and said nobody would be allowed to get away with bad behaviour.
Now, Formula One officials have warned if it ever happens again they will be handing out punishments.