The first leg of the last 16 tie took place in the English capital and Ernesto Valverde's side were the favourites to win the clash. However, things did not go as per the Catalan club's plan during their trip to London.
Chelsea dominated the game and Willian came close to score two goals in the first half, only to be denied by the post both occasions. The Brazilian was successful in getting his name on the scoresheet when he gave the Premier League winners the lead in the second half.
Keown was delighted with the former Juventus and Italy coach's tactics and was happy that Chelsea players worked hard to execute their manager's plan.
"Antonio Conte's counter-attacking set-up was perfectly suited to dealing with Barcelona's dominance. But what made this performance was how up-for-it his players were," Keown told the Daily Mail.
"Conte has not always looked interested this season - he barely left his seat during the defeat at Watford - but he was so fired up on Tuesday night and his players responded, working very hard to make Barca look ordinary."
Barcelona pulled one back after a mistake from Andreas Christensen allowed Andres Iniesta to assist Lionel Messi to score the equaliser. Keown was critical of the 21-year-old Danish defender and slammed him for being "too casual".
"Inexperience cost Andreas Christensen. He played a blind pass across goal and it was duly punished — though Cesar Azpilicueta could have rescued his team-mate had he stayed on his feet, instead of diving in," the former Arsenal defender stressed.
"Playing across your own goal is widely considered the cardinal sin for a defender but, to be fair to Christensen, the modern centre back is encouraged to play out from the back and had his pass found a team-mate we would have thought nothing of it.
"The issue was that he was careless, too casual in a game where full concentration for 90 minutes was required. Aside from this passage of play, Chelsea very nearly did play the perfect game."
Barcelona have an advantage of an away goal. The second leg between the La Liga leaders and Chelsea will be played at Camp Nou on 14 March.