The Greece international was forced off the field in the 35th minute after a shoulder barge on the touchline by Bukayo Saka sent him flying off the pitch and into coach Jurgen Klopp.
In the process, the Greek landed awkwardly, visibly wincing in pain as he clutched his shoulder area.
The Liverpool medical team didn't hesitate or attempt to treat the player on the pitch. He was immediately replaced by Joe Gomez.
Tsimikas was taken straight to hospital with early reports suggesting that he has suffered a broken collarbone.
Short of options
With Andrew Robertson already missing for the Reds, this latest injury could be a major blow for Liverpool at this very busy time of year.
Gomez, who replaced Tsimikas on the day, has played at left-back on many occasions but, as a right-sided player, it's not his natural position.
Youngster Luke Chambers, a natural left-footer, is likely the next player in the pecking order for the role.
Likewise, Tsimikas' injury could create an opportunity for 18-year-old Calum Scanlon.