https://www.atptour.com/en/rankings/singles
In the Dubai tournament, D. Thiem lost to Harris which was quite surprising, and in 2021 he has not yet shown an impressive performance.
And a little note to this, after 16 years Medvedev is the first outside from the TOP 4 players (Djokovic, Nadal, Federer and Murray) who manages to get into the TOP 2. As an Austrian, I would have been happy if it had been Thiem, but he seems to have a drop in form at the moment.
https://kurier.at/sport/tennis/nach-djokovic-federer-und-co-tennis-star-daniil-medwedew-schaffte-historisches/401219058