Mariners right-hander Felix Hernandez is expected to miss four to six weeks after an MRI revealed a Grade 1 lat strain, per Corey Brock of The Athletic (Twitter link).

The injury to Hernandez comes as the Mariners were on the verge of getting left-hander Wade LeBlanc back into the rotation after a stay in the injured list. Instead, they’ll continue to operate without one member of their season-opening rotation, meaning young righty Erik Swanson could get an extended look in the rotation alongside Yusei Kikuchi, Marco Gonzales and Mike Leake. LeBlanc pitched in a rehab game in Triple-A yesterday and is seemingly close to a return.