Naomi Girma, women's soccer's first million-dollar player, was injured and replaced in her Chelsea debut on Sunday.
The United States defender was taken off after 59 minutes of a 2-2 draw against Brighton and it was not immediately clear how serious the unspecified injury was.
"We'll need to assess her tomorrow, but it doesn't look too bad, but we will see," Chelsea coach Sonia Bompastor said.
The 24-year-old Girma joined Chelsea from the San Diego Wave FC in January for a reported fee of £900,000 ($1.1 million). That deal surpassed the previous world-record fee of $788,000 that Bay FC paid to sign Zambia striker Racheal Kundananji from Madrid CFF last year.
Girma was replaced by Nathalie Björn in the Women's Super League game at Brighton's Broadfield Stadium.
"She's learning about the league, the team and her teammates. As you could see, the first game is never easy because it's a competitive league," Bompastor said. "It was good for us to have her start this game, building minutes and being able to play with the team."
Five-time defending WSL champion Chelsea secured a point through Lauren James' equalizer in the 61st minute.
Chelsea led through Sandy Baltimore's opener in the 16th, but Brighton went into half-time up 2-1 after goals from Marisa Olislagers in the 22nd and Vicky Losada in the 42nd.
Chelsea are five points ahead of Manchester United at the top of the standings.