Albion boss Carlos Corberan, chief executive Ron Gourlay and head of recruitment Ian Pearce look set for a busy final day of the January transfer window, with efforts being stepped up following back-to-back defeats for the Baggies.
Corberan's men were flying before a late defeat at Championship leaders Burnley, then tumbled out of the FA Cup at the weekend following a poor display at Bristol City.
Winger Matty Phillips, who has been a revelation since Corberan replaced the sacked Steve Bruce at The Hawthorns, could miss the rest of the season after going under the knife at the weekend for an operation on a serious quad muscle injury.
Several clubs including Stoke City are interested in signing forward Karlan Grant on loan - but Corberan is only likely to sanction departures if he can get some fresh blood in himself.
Forest midfielder O'Brien worked with Corberan at Huddersfield Town, and the Spaniard was keen on a reunion until Steve Cooper's side inserted an obligation to buy clause of £10m at the end of the loan deal.
Money is tight for Albion, ruling them out of the running for O'Brien and leaving Championship promotion chasers Sheffield United in pole position to sign him.
Villa midfielder Nakamba is now reportedly on Corberan's wanted list, as he is not in Unai Emery's plans and is free to leave Villa Park having struggled to make an impression since moving to the Midlands in an £11million deal from Club Brugge in 2019.
Fulham's Nathaniel Chalobah is also believed to be on Albion's radar and Corberan told the Express & Star: "We have time to fix the needs and cover what we need to cover, what we understand - me, with my club, with Ron (Gourlay), with Ian (Pearce) - what we have to cover.
"We still have the days to fix the points we need to fix.
"Of course, in my mind, I had one idea to improve the team. But after the situation with (Matt) Phillips of course we have lost one player probably till the end of the season and it's something we need to fix."
Albion have seen one player head through the exit door on Monday, with veteran defender Martin Kelly joining Wigan on loan for the rest of the campaign.
Former Albion striker Oliver Burke, meanwhile, has joined Millwall on loan from Werder Bremen until the end of the season.
The attacker returns to the club just one year after a previous loan spell, where he scored twice in 14 appearances.
Burke, 25, has represented Scotland 13 times, scoring one goal, and has played for Nottingham Forest, Bradford, Sheffield United and the Baggies.