Neco Williams gave the visitors an early lead on for Julio Enciso to level things up for Ipswich just before half time.
Arguably the most interesting moment of the game wasn’t a goal, however, it was when Diop brought James McAtee down when the Forest ace looked to be through on goal.
Initially referee Thomas Bramall waved it away without even awarding a free kick, but VAR took a look to see if Diop had in fact denied an obvious goalscoring opportunity.
Bramall was called over to the monitor to take a look, but instead of brandishing a red card as many had expected, he showed a yellow.
Speaking to Sky Sports after the game, Diop agreed with the referee’s decision, saying: "I don't think it's a red, I went to tackle because I saw Leif Davies covering.
“He (James McAtee) puts the ball wide and Leif was there to cover. I don't think it's a red. I was quite confident about that."