Ange Postecoglou’s men came racing out of the blocks in the derby clash and took the lead after just five minutes when Reo Hatate scored.
Rangers were on the ropes and could not contain Celtic, who scored another two times before the half time whistle, with Hatate helping himself to a second and Liel Abada scoring.
Celtic eased to a 3-0 win, taking all three points and knocking Rangers off the top of the Scottish Premiership standings.
McManus admits that he has learned a lesson through the performance as he underestimated Postecoglou due to the fact he had not played or managed in a top league.
He feels that Postecoglou was dealt a bad hand on taking over at Celtic, but has built a superb team packed with speed and talent.
“Think a few folk have learned a valuable lesson (myself included) in not to write people off because you haven’t heard of them or they haven’t played/managed at top level”, McManus wrote on Twitter.
“He was dealt an awful hand coming in but has built a quality team full of pace and skill.”
Celtic now boast a one-point lead over Rangers at the top of the Scottish Premiership table with 24 games played so far.
