I just had to buy this advert from summer 1980 after reading what is written in the ad.
They write that this smurfs is known to his friends as Bjorn Smurf.
Since the Swedish tennis-legend Björn Borg won Wimbledon 5 years in a row between 1976 and 1980, he is off course the tennisplayer they mean.
Almost like when they wrote "like a bolt of lightning" in the adverts for the Sprinter made for the summer Olympics in London. Then refering to Usain Bolt.
I just love adverts like this.