With Keller playing, and his childhood pal Jakob Chychrun also in the lineup, they will become the first 18-year-old duo to skate in the same game for the Coyotes/Jets franchise since Shane Doan and Jason Doig did so on Oct. 9, 1995.
Doan, of course, is still with the Coyotes at age 40. However, Doan is expected to miss his sixth consecutive game because of a nagging lower-body injury.
Meanwhile, center Alex Burmistrov is expected to play after missing the past 13 games because of an upper-body injury.
St. Louis (40-28-6) has won nine of it past 11 games and currently owns the second wild-card spot in the Western Conference.
The Blues have dominated the Coyotes recently, winning nine straight games between the teams; they haven't lost in regulation to Arizona since April 6, 2012.
Goalie Jake Allen has posted a 6-0-0 record, two shutotus, a 1.00 goals-against average, and a .962 save-percentage vs. the Coyotes in his career.
Forward Vladimir Tarasenko leads the team and the Western Conference with 34 goals.
Captain Alex Pietrangelo will enter the game with 40 points, including five power-play goals, which rank sixth in the NHL for defensemen.