AC Milan star Zlatan Ibrahimovic tested positive for coronavirus on Thursday but responded: "Covid had the courage to challenge me. Bad idea."
"I tested negative to Covid yesterday and positive today," said Ibrahimovic, who turns 39 in a week's time, on Twitter.
"No symptoms whatsoever. Covid had the courage to challenge me. Bad idea."
The Swede is now self-isolating and missed the team's Europa League third qualifying round tie against Norwegian club Bodo-Glimt in the San Siro Thursday.
The positive test is a blow for Ibrahimovic who has been in stunning form despite his advancing years.
He scored a double in Milan's Serie A opener against Bologna on Monday having also netted against Irish side Shamrock Rovers in the Europa League.
"It is a heavy, unexpected absence," said Milan technical director Paolo Maldini.
"He was very sorry because he is in overflowing physical condition and unfortunately has an ongoing infection.
"The hope is to eradicate the disease soon and be available again. In seven days he will be available in my opinion," added Maldini.
Ibrahimovic is expected to miss the next two Serie A games against Crotone and Spezia.
The Swede will most likely be available again after the international break for the Milan derby against city rivals Inter on October 17.
"Ibrahimovic has tested positive for Covid-19 following a second round of swab tests ahead of tonight's game against Bodo/Glimt," Milan said earlier.
"The club has informed the relevant authorities and the player has been promptly placed in quarantine at home. All other team members and staff have tested negative."
The second round of tests were carried out after Milan's Brazilian defender Leo Duarte returned a positive swab for Covid-19 on Wednesday.
Milan recruited the forward in January on a six-month contract after leaving Los Angeles Galaxy, on a deal worth 3.5 million euros ($3.9 million) with the option for an additional season.
The former Manchester United, Paris Saint-Germain and Barcelona player had a big impact, scoring 11 goals in 20 games.
Last month he reached an agreement on a new deal for another season reportedly worth seven million euros ($8.3m).
The seven-time European champions moved up from 11th on his arrival to sixth, finishing the league season on a 12-game unbeaten run.
Ibrahimovic is in his second spell at Milan after also helping them to the most recent of their 18 Serie A titles in 2011.
He also won three league titles with Inter and two with Juventus which were both revoked because of the 'Calciopoli' match-fixing scandal.