Ole Gunnar Solskjaer's side have rallied manfully after a poor run, with the draw against table-topping Liverpool followed by three successive wins on the road in all competitions.
Rashford's stunning free-kick secured Wednesday's 2-1 Carabao Cup triumph at Chelsea, but the in-form forward has to be assessed ahead of the trip to Bournemouth after coming off with what appeared to be a knee complaint.
Lindelof was also replaced with a knock in the second half and Maguire looked in discomfort despite completing the last-16 clash at Stamford Bridge.
"It's still early," United manager Solskjaer said of the trio. "Hopefully we can get them back on the pitch tomorrow.
"They had some treatment yesterday, a little more treatment today, a light session and hopefully they're ready. I can't tell you exactly now."
United could be without as many as nine first-team players at the Vitality Stadium.
Eric Bailly is a long-term absentee, Diogo Dalot has missed recent matches and Paul Pogba remains sidelined with an ongoing ankle injury.
Solskjaer does not expect the World Cup-winning midfielder back until after the international break - the same timescale facing Axel Tuanzebe, Nemanja Matic and Luke Shaw.
"They're not ready for tomorrow, that's the update," the United boss said. "Probably after the international break.
"That is always the risk if you push them back too early, but if we have the two extra weeks after the international break, they should all be ready for then."
United head to the south coast for Saturday lunchtime's encounter buoyed by wins on the road at Partizan Belgrade, Norwich and Chelsea - an impressive reaction to their 11-match winless away run.
"That's football - sometimes you get luck of the dice," Solskjaer said. "Sometimes you don't. The game on Wednesday night was decided by an unbelievable strike by Marcus, obviously.
"In Belgrade, we defended really well - some great last-ditch defending there - and Norwich I think was a good game.
"The confidence is getting better, getting players back from injury helps, but in football it's not very far from failure to success or the other way around.
"It's hard to evaluate after just 10 games and some cup games, but there have been some fine margins.
"We've played really well at times. We've developed a team spirit, an identity, more intensity, aggression in the team and suffered a bit from injuries."
United's character is being epitomised on and off the field by Scott McTominay.
Named United's player of the month for September, the 22-year-old is up for October's award as the academy graduate continues to impress in the centre of the park.
"He's been excellent," Solskjaer said. "Now, him and Fred work, they're working in a good relationship, they played well together.
"They did that last season, PSG, Arsenal, there was quite a few games there they played together when we had some injuries and now as well they're working as pair.
"But Scotty's been excellent. He's a leader, he's a Man United boy, he's gone through the ranks.
"You can see he's been a striker with the goal he scored against Norwich on the half turn, but he's developing into a very good midfielder."