Cristiano Ronaldo suffers apparent hamstring injury in Portugal's Euro 2020 qualifier against Serbia

Cristiano Ronaldo suffered what appeared to be a hamstring injury in Monday's Euro 2020 qualifier against Serbia, causing concerns for Juventus as a Champions League clash with Ajax looms.

The forward lined up for Portugal in Monday's qualifying clash, but was forced out of the match in the 31st minute due to the injury.

At the time, Portugal were losing 1-0 to Serbia thanks to a Dusan Tadic finish from the penalty spot. However, shortly after Ronaldo's removal, Portugal were able to tie the match through a goal from Danilo Pereira.

Ronaldo was instrumental in guiding Juventus past Atletico Madrid and into the Champions League quarter-finals, as the former Real Madrid star fired home a hat-trick to help the Italian side overcome a 2-0 first leg deficit.

Now, his status for that quarter-final, a clash with Ajax, is up in the air depending on the severity of his injury.

Juventus are set to take on Ajax on April 10 in the first leg in Amsterdam before returning to Turin for the second leg six days later.

Watch Champions League | Soccer Live Streaming | DAZN CA

Ajax sealed their spot in the quarter-final round by stunning Ronaldo's former club, Real Madrid, battering the Spanish giants 4-1 in the second leg at the Bernebeu to advance in the competition.

Before facing off with Ajax, Juventus do face a trio of Serie A matches at the conclusion of the international break.

The Serie A leaders will return on Saturday against Empoli before facing Cagliari three days later. Juve will then take on AC Milan on April 6 ahead of the trip to the Netherlands.

In league play, though, Juve have all but wrapped up the title, having established a 15-point lead on second-place Napoli and a 22-point lead on third-place Inter Milan.

Ronaldo has been pivotal to that Serie A lead, having scored 19 goals in 26 league appearances since joining the club from Real Madrid this past summer.

He's scored a further four goals in Champions League play as he looks to guide Juve on a tournament run having won the last three titles during his time in Madrid.

Ronaldo also started and played all 90 minutes on Portugal's Euro 2020 qualifying opener, a scoreless draw with Ukraine.