Tottenham kept their slim Premier League title hopes alive with a 4-1 demolition of 10-man Southampton at St Mary's on Wednesday night.
The victory saw Spurs move 10 points behind leaders Chelsea but Pochettino's side are now only one behind Arsenal in the race for Champions League qualification.
Though Keown is a big fan of the Lilywhites and its manager, the ex-Arsenal defender feels that Europa League football - and particularly playing on Thursdays - could hinder the Argentine and his troops in the second half of the campaign.
"I have been immensely impressed with the way that they play and the calmness of their manager, Mauricio Pochettino. He has an unstinting belief in his players," he wrote in The Mail.
"However I do feel that playing on a Thursday night in the Europa League will not help them in the second half of the season."
Tottenham dropped into the Europa League after finishing third in their Champions League group, which contained Monaco, Bayer Leverkusen and CSKA Moscow.
They will have to contend with the rigourous Thursday-Sunday schedule from February and the further they go in the competition, the worse it could be on their Premier League form.