The Chicago Cubs were dealt some bad news when starting pitcher Jake Arrieta left Monday’s start against the Pittsburgh Pirates with what the team is calling an “apparent right leg injury.”

The injury certainly did not look good for the 2015 National League Cy Young Award winner when it happened.

Arrieta had baseball’s best second half ERA (1.59) entering the start. Including Monday’s start, he has a 3.48 ERA on the season. With the Milwaukee Brewers loss on Monday, Chicago began play against Pittsburgh with a four-game lead in the National League Central.

Any long-term injury to Arrieta would make the division race more interesting and would certainly hinder the Cubs’ chances in the postseason.