Lahr's first playing time with the team came in 1949, when Cleveland again won the AAFC championship. Brown came close to cutting Lahr when he made a mistake on defense during a preseason game against the San Francisco 49ers. Lahr, however, made the team and started the year as a left halfback. He was switched to safety in the middle of the season and played primarily on defense after Browns starter Cliff Lewis was injured. Substituting for Lewis, Lahr quickly became a regular starter on defense and finished the year with four interceptions. One of his interceptions came at the end of a divisional playoff game against the Buffalo Bills and helped the Browns retain a 24–21 lead.