Jokic, who was listed at 129kg to start the season, looked sluggish at times throughout the campaign despite the Nuggets sitting in the third seed in the West.
The 25-year-old was averaging 20.2 points, 10.2 rebounds, and 6.9 assists per game when the season came to a stop due to the Covid-19 pandemic.
Photos of his transformation have since been posted to Twitter, leaving fans in awe.
"Wow his twin brother is in really good shape," one fan joked, while another commented, HUH!?!? Are we sure that's Jokic!?"
Meanwhile, another European NBA star, Luka Doncic, is apparently not quite where he needs to be.
"He's not in the best shape," his trainer Jure Drakslar said, per the Dallas Morning News.
"Which is normal. NBA games will not be played before the end of July, so there is enough time to help him recover and get ready.
"However, he undoubtedly would be ready to play right now."