The defender was at his best as the Black and Gold came back from three goals down to force a 3-3 draw with Toronto FC on Saturday.
He lasted for the entire duration of the game at the MAPFRE Stadium in Columbus, Ohio.
"When I think of the second half that he [Afful] played, [it] was amazing," said, Berhalter, who earlier singled the 31-year-old out for compliment after last month's 1-0 win over Philadelphia Union.
"The relentlessness. When we talk about how you give the defense trouble, it’s running behind their line, and he did that over and over and over again.
"To me, it was an exceptional performance by Harrison as the game went on in terms of how he competed and how he got himself into this game."
Afful has made 14 league appearances, all full-time outings, so far for Crew this season.
He also has a goal to his name, having netted in the 2-1 triumph over San Jose Earthquakes in April.
Currently in his fourth season with the Black and Gold, the Ghanaian joined from Tunisian outfit Esperance in 2015.