By Sam Bush

Phillies hurler Zach Eflin may be the first casualty of 2017 spring training.

Eflin could not throw Friday because of swelling in his right knee, but he said he is scheduled to have a bullpen session tomorrow

Eflin, 22, had surgeries last year to repair the patellar tendons in his left and right knees following 10-12 years of chronic issues. He said earlier this week that his knees felt great. But then he tweaked his right knee running sprints on Thursday.

“Nothing is structurally wrong,” Eflin told MLB.com yesterday at Spectrum Field. “It just swelled up on me a little bit. But today I came in and everything was fine. I got all my rehab done.”

Eflin joined the Phillies in December 2014 following the Jimmy Rollins trade with the Dodgers. He made his big league debut June 14, allowing nine runs in 2 2/3 innings against the Blue Jays, but he posted a 2.08 ERA in seven starts from June 19 to July 22.