Key Newcastle injuries concern Howe ahead of 'dangerous' Chelsea clash
Defender Fabian Schar and midfielder Joelinton, injured during Newcastle's win over Fulham on Sunday, had scans that didn't seem "too bad" but were not a certainty, Howe told reporters on Monday.
"To miss Fabby would be a big blow," he said, referring to Schar.
Forward Alexander Isak also missed Sunday's match with a groin injury but it was not too serious, Howe added.
"We need to treat him carefully to make sure he isn't out for six or seven weeks. He has a chance for tomorrow but we need to be careful," the English coach said.
But one major boost for Newcastle was centre-back Sven Botman's return from a three-month knee injury.
"There are certain players who lift the team in particular and Sven is one of those. He gives players confidence around him and makes a big difference," Howe added.
Newcastle have never won the League Cup, finishing as runners-up in 1976 and last season. However, Howe believed their experience of getting to Wembley in February was helping them in this campaign.
"We've seen the rewards you can get from it. The build-up to the final was a brilliant thing to be part of... it was incredible to see how many fans we took to London. It's helped us this year," he said.
Chelsea have more of a pedigree in the competition, having won the League Cup five times, most recently in 2015. They have struggled this season though their home form has vastly improved since the end of October.
However, Howe was confident Newcastle could end their five-match winless streak in away matches in all competitions.
"We beat Manchester United away and were seconds away from beating Paris (St Germain). I don't doubt our character. We're certainly up for the fight," he said.