Nine European countries participate in the EuroMillions lottery
A second person has come forward to claim a share of the 100m euro (£91m) Euromillions jackpot, according to the National Lottery operator.
The record-breaking cash prize was won by two British tickets following the draw on Friday.
Camelot said it still had to verify the claim for £45,570,835.50 - the UK's largest ever lottery prize.
If one person, rather than a syndicate, owns either ticket it will also be the UK's biggest ever individual win.
Until now, the record single win was by former Royal Mail worker Angela Kelly, from East Kilbride, South Lanarkshire, who scooped £35.4m in August 2007.
Champagne on ice
Camelot said no details of Friday's winners would be released until Monday at the earliest to allow time for the claims to be verified and the money paid out.
"We have plenty of champagne on ice and are looking forward to welcoming the lucky ticketholders to the National Lottery millionaires' club," a spokeswoman added.
The winning numbers on Friday were 19, 43, 45, 34, 11 and the Lucky Star numbers were 5 and 9.
Nine European countries participate in the EuroMillions lottery - Britain, the Irish Republic, France, Spain, Portugal, Austria, Switzerland, Belgium and Luxembourg.
In May a ticket bought in Spain broke the European lottery's record by netting a 126m euros (£110m) jackpot.