Tottenham Hotspur and Arsenal look to be among the leading contenders to win the Premier League this season, alongside Leicester City and Manchester City.
And Keown believes that neither side can afford to lose at White Hart Lane when they meet next month.
“I think it has to be the biggest derby of Arsene Wenger’s reign, if not the biggest ever. It’s certainly the most important in the history of the Premier League,” Keown said.
“Without being disrespectful to Tottenham, this fixture lost some of its importance in recent years. Of course it’s a derby game you have to win but at Arsenal our rival became Manchester United, because they were the ones we were challenging for the league.
“Now with Tottenham performing as they are, I can’t think of a derby bigger than this.
“There’s still a few weeks to go until the game on 5 March but Tottenham’s current form has to make them favourites. And in recent years I think this was a game Arsenal could afford to lose but still go on to have success. Not this time.
“This is a game neither side can afford to lose but if they win, it is such a huge step towards winning the league, as long as you keep the consistency either side of it.”
Tottenham currently lead Arsenal in the table, but they are only ahead of Arsene Wenger’s side on goal-difference.
The two London rivals have been locked together all season, and they have proven very hard to separate.
Tottenham last finished ahead of Arsenal in the 1994/95 season, meaning Mauricio Pochettino’s side have a chance to end a long and punishing wait to end the campaign above their local rivals if they can finish the season strongly.
When Spurs and Arsenal met earlier in the season at the Emirates Stadium they played out a 1-1 draw.
On that day Harry Kane put Tottenham ahead in the first-half, but the Gunners hit back and scored late on through Kieran Gibbs.