He was also competent on the offensive side of the ball, pulling down five passes for touchdowns during his 1934 season in helping lead the team to a 9–1 record.

In 1935, Klewicki signed a pro contract with the Detroit Lions and was a member of the NFL's World Championship team that season, starting 7 games at left end.

In the early minutes of play, Lions' coach Potsy Clark decided to surprise the Giants with a shotgun offense.

Glenn Presnell, the Lions' passer, fired a long pass intended for Klewicki, but the ball hit New York Giants' Ed Danowski's chest.

Ace Gutowsky plunged for a touchdown, Presnell kicked the extra point and the Lions led 7–0 on their way to the championship.