Celtic are looking at their Lennoxtown training pitches as the club seek an explanation for a lengthy injury list.
"We are looking at the surface here," said manager Neil Lennon.
"It can be quite slippy when it gets wet and it may have an impact on a couple of soft tissue injuries that we've picked up, but you can pick them up at any time.
"We have tempered training a little bit as well and obviously the boys will not be doing much between now and Sunday."
Celtic visit Motherwell at Fir Park, knowing a win would lift them above the hosts into second place in the Scottish Premier League.
But Lennon's options have been limited by a long list of casualties, with defender Mark Wilson the latest player set for a prolonged period on the sidelines.
Kelvin Wilson, Emilio Izaguirre and Scott Brown have already missed large chunks of the season.
Mo Bangura, Charlie Mulgrew and Joe Ledley also missed Thursday's Europa League win over Rennes through injury and Lennon handed 17-year-old Marcus Fraser his debut when Glenn Loovens had to come off at the interval with a recurrence of a hamstring complaint.
"When you consider the players that we have out with long-term injuries; Izaguirre, Brown, Kelvin Wilson, key players, it has been stop-start in terms of trying to put a team out on a regular basis," added Lennon.
"We were trying to count the players who have not been injured this season and I think we were at four or five out of the whole squad.
"It is not an excuse, it is a plausible reason."
Celtic spent £8m developing the training complex that was opened in 2007 and includes three full-sized grass pitches.
Celtic trail Motherwell by three points and lag 12 points behind SPL leaders.
And Daniel Majstorovic believes the constant tinkering with the defence, due mostly to injuries, has contributed to Celtic's sluggish start to the season.
"Of course, there has been a lot of changes and almost every game we have a totally different back four," said the Sweden centre-half.
"I think that is a reason we haven't performed as well.
"We have a lot of injuries at the moment, which isn't good, but it proves we have a big squad and you saw yesterday's performance, that was a positive."
And Lennon believes the impressive 3-1 win over Rennes is a timely boost for his side.
"They should be feeling good about themselves," he added. "It will give them a huge lift.
"It was the ferocity of the performance that I liked, and the team work and togetherness.
"The huge bonus was bringing in Marcus Fraser at 17, he coped brilliantly. To beat a team like Rennes with all that was surrounding the game was a credit to the players.
"Now it is back to business and we want to get a positive result on Sunday."