Derrick Williams looks set to miss the start of the season through injury.

The Republic of Ireland international, who became a dad for the first time this week, is yet to feature so far in pre-season because of a calf problem.

A six week diagnosis will see the 25-year-old be unavailable for the start of the season which gets under way against Charlton on August 3.

Williams finished last season in excellent form for Rovers, starting the final six matches alongside Darragh Lenihan in central defence.

The former Bristol City man was left frustrated by injuries last term, as well as two red cards, which saw him restricted to just 29 appearances in all competitions having started all but one of the League One matches the previous season.

On his injury, Mowbray said: “A calf strain. It’s a real frustration for us.

“It was going to be a six week injury so he’s been unavailable for us so far.”

Big money signing Sam Gallagher didn’t travel with the squad to Rangers having arrived earlier in the week from Southampton.

Mowbray didn’t feel the game was the right one to throw the 23-year-old in to but he could feature at Bury on Wednesday night.

The striker made an appearance off the bench in a behind closed doors game against Macclesfield last week.

And Mowbray said: “Sam Gallagher has trained hard in the few days he’s been with us but this wasn’t a game that wasn’t right for him so we left him at home so I didn’t have the temptation to put him on.”

The fitness of Harry Chapman is also being monitored, with the winger having featured in just one behind closed doors game so far.

Midfielder Jacob Davenport, who was taken off in the game against Macclesfield, will also miss the early weeks of the season with a knee injury.