Lennon's team have endured a far from ideal preparation for the crucial tie after conceding 12 goals in four friendly defeats on a pre-season tour of Germany disrupted by injuries and star sales.
Adam Matthews, Gary Hooper and Joe Ledley are all expected to be sidelined, while Kenya midfielder Victor Wanyama, a key figure last season, has been sold to Southampton.
"It's so early, it's a harsh reality of where we are," Lennon said. "We won the cup final at the end of May and we are back in on June 24.
"It's been staggered and a bit disjointed because we have had a lot of injuries as well.
"I don't even know what my best team is at the moment or which players I'll have available to me.
"They are the ups and downs you have to cope with during pre-season, but I don't think you'll see us anywhere near our best for another two weeks or so.
"We know how difficult it's going to be because these games are so early in the season. We'll cover it as best we can but it won't be easy for us."
Despite the financial gulf that separates the two sides, Lennon has warned his players against complacency against the team of part-timers, whose tiny Solitude ground has been extended to allow a 5,000 capacity crowd.
"What we can't get involved in is the party or the carnival atmosphere," Lennon said. "We have to be professional and go there to do a job."