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Since England's second tier was rebranded as the Championship in 2004-05, Ivan Toney's 31 goals last season for Brentford had represented the benchmark.
However, Mitrovic's remarkable season continued in Fulham's 2-1 win over Peterborough United, his 30th appearance of 2021-22.
The Serbia international's opener from the penalty spot passed Toney's mark, before his second extended his own record and ensured the league leaders took all three points.
Mitrovic, who also played in the division for Newcastle United before joining Fulham, now has 75 Championship goals in just 116 appearances.
That compares favourably with his rather underwhelming return of 24 goals in 104 in the Premier League.
The last player to score more in the second tier was Portsmouth's Guy Whittingham, who hit 42 in 1992-93, although even that pales next to George Camsell's ludicrous 59 Middlesbrough goals all the way back in 1926-27.
Perhaps with those two now in his sights, Mitrovic said: "I've had quite a few records, but this feels nice. I broke the record with the Serbia national team as well, and now today here. I feel good, I feel great in this team."
Fulham boss Marco Silva added: "The best team on the pitch deserves the three points; congratulations for our players and now let's talk about Mitro. Congratulations for him.
"The numbers speak for themselves. I cannot say anything more. 33 goals at the end of February with 14 games to play – they are fantastic, fantastic numbers.
"What I like more from him is that he's always demanding more and more and more. He knows that from tomorrow I will demand more and more from him. The team-mates will do the same as well.
"But first we are happy, because it's not just Mitro's number, it's something more, it's something that reflects our philosophy as a club, as a staff."