Edinburgh Monarchs captain Josh Pickering suffers suspected broken collarbone
The 26-year-old Australian crashed on the first bend of the opening heat in last night's 51-39 defeat to the Berwick Bandits and had to be withdrawn from the meeting at Shielfield Park.
He was due to go to the nearby hospital to have it checked out, but Harkess insists his rider is fearing the worst.
It rounded off a disappointing 24 hours for the Monarchs in this year's BSN Series after losing the reverse fixture at Armadale on Friday night.
However, their biggest dilemma is sourcing a suitable guest to replace Pickering ahead of this week's crunch KO Cup quarter-final clash with the Oxford Cheetahs.
"Josh's own diagnosis is he's broken his collarbone," Harkess told the Evening News. "He says he's had it before, and with the way he's carrying it, but he was going to the hospital to get it checked. He could be out for four, maybe six weeks - I don't know the answer.
"We will go with guests in the meantime. We won't be looking at a replacement for Josh so we'll be using guests, initially for our matches with Oxford this week coming and then we'll see where we are after that.
"Our season hasn't got off to the best of starts and we struggled last night at Berwick. Craig Cook has been ill all week - he started well but his energy ran out and he couldn't hold onto the bike any longer. You can't do a match without your No.1 and No.5 and there was no obvious winner among the rest. They were all capable of doing something but not going out and winning races.
"We need Cookie fit and we need a suitable guest to take on Oxford on Wednesday and Friday and then after that we can start focusing on our league matches. The Knockout Cup has always been a big competition for us, we generally go well in it. Oxford is not an opposition I would have liked as early as this but it is what it is.
"Friday night was a much bigger disappointment than last night. I'd like to think there won't be another night at Armadale like that this season."