Portland Thorns forward Sophia Smith was crying as she limped off the field with an apparent right knee injury during Sunday's road draw against Washington Spirit at Audi Field in the NWSL.

Smith, 23, walked out of the medical tent in crutches before heading into the locker room. The injury happened when she slid inside the box and seemingly overextended her knee.

Hannah Betfort replaced Smith on the field as the first half drew to a close with both sides scoreless.

Smith favored her right leg as a medical staff member, who conducted stability tests on the knee, helped her off the field.

Spirit midfielder Andi Sullivan, Smith's USWNT teammate, also helped her up and looked extremely concerned.

Thorns, Spirit tie with one goal each

Smith also had ice wrapped around her right knee and was seemingly able to plant the foot, albeit gingerly.

Morgan Weaver put the Thorns in front at the 64th minute, but Spirit tied the contest during injury time with a penalty by Ashley Hatch.

Smith, the reigning league MVP, will be a huge loss for the table-topping Thorns. There will be further information after she undergoes an MRI.

Portland visit Racing Louisville on Saturday, September 2.