Anthony Wordsworth is poised to miss at least the next six weeks after it was confirmed he has cracked three vertebrae in his back.
The Ipswich midfielder, a January signing from Colchester, made his full debut in Saturday's 1-0 win over Blackpool but was forced off after just 35 minutes following a clash with Blackpool goalkeeper Matt Gilks.
Wordsworth will not require surgery but will now need to rest for six weeks before starting to regain his match fitness.
Daryl Murphy picked up a late knock in the weekend victory but is expected to be fine for Tuesday's visit of promotion-chasing Watford.
Meanwhile, winger Lee Martin (hamstring) and goalkeeper Scott Loach (sprained thumb) will both return to contention against the Hornets having missed out of late.
Saturday's success over Blackpool moved Town four points clear of the drop zone.
Watford welcome back Joel Ekstrand but fellow defender Fitz Hall remains sidelined.
Ekstrand missed the 2-2 draw with Crystal Palace as well as Saturday's 4-0 victory at Birmingham with a knee injury but is back in the fold for the Suffolk encounter.
Hall, meanwhile, sat out the weekend's impressive triumph at St Andrew's nursing a hamstring complaint and will be again be missing against an Ipswich side embroiled in a relegation scrap.
Fellow defenders Tommie Hoban (ankle) and Neuton (back) also remain sidelined.
Manager Gianfranco Zola must decide whether to tinker with his line-up as the Hornets face their second of three games in the space of a week, with the likes of Ekstrand, Jonathan Hogg, Fernando Forestieri and Alex Geijo, among others, competing for recalls.