Starter Vladislav Stoyanov is suspended for the Anfield game while Ivan Cvorovic is out with a shoulder injury. The side does have Georgi Argilashki available.
The Bulgarian team advanced to the group stage of the Champions League for the first time when it edged Steaua Bucharest 6-5 on penalties. Defender Cosmin Moti, in for the red-carded Stoyanov, saved two penalties in the shootout.
Borjan, who started for Canada in a 3-1 win over Jamaica last week in Toronto, had been without a club. The 26-year-old has had club stints in Argentina, Serbia, Turkey and Finland.
A Canadian Soccer Association official confirmed his signing with the Bulgarian team.