Liverpool star Virgil van Dijk labelled Barcelona great Lionel Messi his toughest opponent.
Van Dijk and Messi went head-to-head last season, when Liverpool produced an incredible second-leg comeback to beat Barcelona in the Champions League semi-finals.
The Netherlands international paid tribute to Messi, a record six-time Ballon d'Or winner who is regarded as one of the greatest players of all-time.
"There are some difficult strikers out there, but probably Leo Messi," Van Dijk wrote on Twitter when asked who his toughest opponent was.
However, Van Dijk also credited Sergio Aguero, having faced the Manchester City forward regularly in recent seasons.
Asked who the hardest player to mark was, the defender replied: "Aguero."
Van Dijk said he was "feeling fine" and would be ready to go when the Premier League season, which is suspended due to the coronavirus pandemic, resumes.
Liverpool held a 25-point lead atop the table when the season was stopped.