Rochdale left-back Joe Bunney and goalkeeper Brendan Moore will be out through injury for at least six weeks and 12 weeks respectively.
Bunney, 23, sustained medial knee ligament damage, while 25-year-old Moore has ruptured his ankle ligaments.
Both picked up their injuries while at the club's training camp in Tenerife.
"I'm looking to recruit in both positions because of the seriousness of the injuries. I'm not prepared to wait and make do," said manager Keith Hill.