The Blues were confident on Thursday of wrapping up the deal by the end of the week but that had not happened before the midday cut-off for Cahill to be registered for Saturday's Stamford Bridge clash.
It remained to be seen whether the Bolton defender would complete what has been a protracted move later on Friday and become Chelsea manager Andre Villas-Boas' first January signing.
If not, Wanderers boss Owen Coyle has already confirmed Cahill would be in contention for his current employers' trip to Manchester United.
An additional 24-hour delay would not necessarily be a bad thing for Chelsea, with Cahill undoubtedly strengthening a Bolton side they will be hoping take points off United on Saturday.
But the more time that passes without an announcement, the more doubt is cast over whether the parties have been able to agree personal terms.
It is now more than a fortnight since Bolton accepted a £7million bid from Chelsea for their prize asset, who was in the final six months of his contract.
Negotiations immediately hit a snag when Blues boss Andre Villas-Boas revealed club and player were "miles apart" in terms of Cahill's salary.
Reports claimed the England international was demanding £100,000 per week, £30,000 more than Chelsea were willing to pay as they seek to reduce their overall wage budget in the era of Financial Fair Play.
There were also suggestions in midweek a compromise figure of £80,000 had been agreed but Cahill trained with Bolton on Thursday morning and there have since been reports Blues chief executive Ron Gourlay had travelled to the north west for further talks.
Villas-Boas was confident on Thursday of a positive outcome "this week" and refused to criticise Cahill or his representatives for the delay.
"It's part of negotiation," Villas-Boas said.
"I'm sure all parties are protecting their interests and we'll reach an agreement."
Chelsea cannot afford the impasse to continue for another fortnight of the January transfer window, which closes in 18 days' time, although Villas-Boas was confident of being able to move quickly for other targets should the Cahill deal collapse.
"We kept a couple of other options available and hopefully we can act quickly if that's the case," he said.
"But I'm pretty confident it will happen."
Further doubts have also been raised over QPR's bid to make Chelsea defender Alex the first signing of new manager Mark Hughes' reign.
The Blues have rejected a reported £3million offer from their west London rivals for the wantaway Brazilian, who it is now said no longer wishes to stay in England.
With Alex frozen out of Chelsea's first team squad, Villas-Boas will be hoping nothing happens to captain John Terry or David Luiz prior to Cahill's arrival.
Terry looks set to shake off problems with both knees to lead out his side on Saturday but Branislav Ivanovic is still out with a hamstring strain.
A defensive injury crisis cost Chelsea dearly against Sunderland last season, when they were stunned 3-0 at home.
The Wearsiders look in even better shape under new manager Martin O'Neill, who has transformed them from relegation fodder to the form side in the Premier League since his appointment last month.
Villas-Boas said: "He's had the right impact and is one of the top managers in the game, with tremendous success here and in Scotland.
"The team were low in motivation and self-belief but they got themselves together to beat the leaders and inspire themselves.
"They can take anyone on, so they're more of a threat now because of that motivation, and Martin is doing such a great job."
There was good news on the injury front for Chelsea on Friday after Florent Malouda returned to training following the knock picked up in Sunday's FA Cup win over Portsmouth that forced him to miss out on Wednesday and Thursday.