Martin Keown believes Celtic have given hope to 19 Premier League clubs following their showing against Manchester City.
The Scottish giants held Pep Guardiola's side to a 3-3 draw in the Champions League on Wednesday night, ending a 10-game winning run under the Spaniard.
Former Arsenal captain Keown was asked in a Daily Mail Q&A, 'Does failing to beat Celtic prove that Manchester City are not invincible under Pep Guardiola?', to which he responded: “Manchester City's draw at Celtic is a chink of light for every other team in the Premier League.
“City showed signs of problems at the back against Swansea last weekend. Swansea did well in the game but lacked the finishing quality that Moussa Dembele showed on Wednesday night.
“It shows that City are still a work in progress and Pep Guardiola will be working hard to get it right.
“His Barcelona team were always able to play themselves out of trouble. Brendan Rodgers had clearly done his homework as Celtic gave City little time on the ball and pressed them high up the pitch.
“Rodgers will have had to go back to the drawing board after Celtic's 7-0 defeat by Barcelona but he has learned fast.
“Understanding the game plan, coupled with the quite-unique atmosphere at Celtic Park, gave Celtic one of their best results and performances in Europe."