According to Marc Berman of the New York Post, Porzingis suggested the Knicks' recent string of games has taken a toll on him: "I'm tired; I'm tired; I'm so tired right now. I have one day to rest my legs and get back and play better and have more energy and try to bring the team's energy up. We're in a tough stretch. The mental part doesn't help at all. When it's mentally tough, you don't have it in you."
Porzingis finished with 16 points and six rebounds in Wednesday's defeat. Only two of those points came in the second half.
The Knicks are in the midst of their worst stretch of the season, as they have now dropped six of their past seven games.
Despite that, they still remain in the Eastern Conference playoff mix, as they trail the eighth-place Indiana Pacers by one game at 18-20.
New York's slide has coincided with a downturn in Porzingis' play, as he has scored 18 or fewer points in three of his past four games.
Overall, Porzingis is likely to earn his first career All-Star nod this year. In 32 contests, the Latvian has averaged 23.8 points, 6.7 rebounds and 2.2 blocks per game.
Along with a tough schedule that included back-to-back games on Tuesday and Wednesday, Porzingis pointed toward Tim Hardaway Jr.'s absence as a factor in his struggles.
"Obviously having Tim out doesn't make it easier," Porzingis said. "Hopefully Tim will be back with us soon and take some of that pressure off me and other guys."
Hardaway is the team's second-leading scorer with 17.8 points per game, but he has missed more than a month of action with a leg injury.
The sliding Knicks will have a day or rest Thursday, but they will be back in action Friday when they travel to Miami to take on the Heat.