The former Sheffield Wednesday and Middlesbrough defender, 47, missed his side's 3-1 defeat at Doncaster Rovers after being sent to hospital on Friday afternoon with chest pains.
Assistant-manager Craig Shakespeare took temporary charge but the performance and result would have done nothing to improve his spirits.
Although the Tigers are without a game this week due to the international break, Pearson will still want to get back to
play a part in transfer negotiations ahead of tomorrow's deadline.
Liverpool defender Daniel Ayala is high on his wanted list but any move may rest on Hull's ability to offload players first.
Midfielder Jimmy Bullard and winger Peter Halmosi are among a number of players that Pearson wants off the wage bill.
Shakespeare said: "We are confident that Nigel will be back in training on Monday morning.
"It was hard to be without him on Saturday because he is a leader and has an aura about him in front of the lads – but his health is the most important thing and we all understood that."
Hull's players had been made aware of Pearson's absence at a meeting at the team hotel four hours before kick-off.
He had been admitted to hospital in Hull on Friday afternoon after complaining to club doctors about the pains in the wake of a training session.
"When they were told, and the importance of it, I could see the shock in their faces," said Shakespeare.
"But they were put in the picture and there were no secrets. One of the reasons we told them early was because we then wanted them to focus on Doncaster."
When Martin Woods headed Rovers in front after just 65 seconds, it looked as if Hull might struggle struggle to come to terms with Pearson's absence.
However, Nick Barmby's ninth minute equaliser refocused their minds and – had it not been for a controversial penalty award that allowed striker Billy Sharp to restore Rovers' lead – the Tigers might just have come away with something.
Ultimately, they failed to turn large periods of possession into goal-scoring chances, and James Coppinger duly added a third
for Rovers with 20 minutes to go.
Referee Lee Mason surprised just about everyone in the ground when blowing for a handball against Hull defender Liam Cooper at a corner. There were just two minutes to go before the interval at the time and the game was sitting on a knife-edge.
"I am really disappointed with the decision," said Shakespeare afterwards.
"I have watched it on the laptop and still can't see why
he gave it! I won't change my mind.
"It was always an uphill battle after that but we took the game to them at the start of the second half and felt we could get back in it," he added.
"However, the manner in which we conceded the third goal was also very disappointing."
Coppinger stroked the ball past goalkeeper Matt Duke after a neat exchange of passes with man-of-the-match Woods. Hull's marking, however, left a great deal to be desired.
It is now 29 games since Hull's last away win and the majority of the 2,942 away fans who made the journey to South Yorkshire expressed frustration at the final whistle.
Shakespeare says the same frustration is being felt in the dressing room.
"If you'd seen the reaction of the players in the dressing room, it was one of hurt.
"We are frustrated as coaches and managers and we have
to, collectively, take responsibility.
"We knew this season was going to be tough – coming in with a team that had got relegated and the financial implications that brought with it. We have to improve all round.
"We have to earn the right to play and we have got to be a bit more resilient individually and collectively," he added.
"We have got to be harder to play against as a team and take it from there."
On the possibility of strengthening, Shakespeare said: "We would like to bring players in but we understand the restrictions the club have in terms of transfers."
Confirming an interest in Spanish defender Ayala, he said: "We will be trying to bend Adam's ear (City's head of football operations Pearson) because we want to try and improve the quality of the squad."
As for Rovers, this victory helped erase the memory of the 4-0 drubbing at Cardiff City seven days earlier and reaffirmed their status as outside contenders in this season's promotion race despite their limited resources.
Doncaster Rovers chairman John Ryan, however, was far from impressed with the Keepmoat Stadium attendance of just over 11,000, especially against a local rival who had been relegated from the Premier League last season.