With the start of the new Premiership campaign just over a week away for Steven Gerrard’s side, the only negative aspect amid their impressive pre-season form so far is the strain being placed on the Ibrox manager’s limited striking options.
Any lengthy absence for Defoe would leave leading scorer Alfredo Morelos as the only recognised central striker in Gerrard’s squad.
“It looks like a hamstring injury,” Gerrard told Rangers TV. “When we know the extent of that, we’ll decide what we need to do.”
Rangers were already looking to strengthen that area of their squad and their hunt for a new striker might now be accelerated ahead of the opening league game against Aberdeen at Pittodrie on 1 August.
“First and foremost we just need to stay calm and find out the extent of the injury, how long it is going to be,” said Gerrard.
"I went on record last week saying I would like to add in that area, in terms of the firepower. It might push us even more in that direction to try and get something done."
Defoe, who signed a permanent deal with Rangers in the summer after his initial 18-month loan spell from Bournemouth concluded, will be 38 in October.
The former England international has maintained remarkable levels of fitness in the latter stages of his career but he was sidelined for six weeks at the end of last season with calf problems.
Ryan Kent, Greg Stewart and Jamie Murphy have occasionally been deployed as central strikers in their careers, but are all regarded as wide players in the Rangers squad.
It again underlines how crucial Morelos will be to Gerrard’s hopes of landing silverware in his third season in charge at Ibrox.
The Colombian international is again being linked with a major move, this time to French club Lille who are believed to be prepared to offer £15 million for the 24-year-old who is under contract at Rangers until 2023.
But his sale would certainly be regarded as unpalatable by Gerrard in the current circumstances.
Rangers have been linked with a move to bring Florian Kamberi back to the club, the Swiss striker having impressed Gerrard during his curtailed loan spell from Hibs at the end of last season.
Kamberi is believed to be on the list of potential signing targets compiled by Rangers sporting director Ross Wilson, although the player himself is not keen on the idea of another loan.
Rangers will continue their pre-season programme with a match against Coventry City at Ibrox on Saturday and it could see Brandon Barker given another chance to force his way into Gerrard’s plans for the new campaign.
The English winger struggled to make an impact last season after joining from Manchester City on a three-year contract. But the 23-year-old former Hibs loanee has caught the eye with lively substitute appearances in the friendlies against Lyon and Motherwell over the past week.
Gerrard believes Barker has the potential to become a significant asset for Rangers in the coming campaign, especially in domestic competition.
“Brandon Barker has put in another positive contribution in for us which I’m pleased about,” Gerrard said after the win over Motherwell.
“We have put the ball in Brandon’s court. We know the talent, we know what he’s capable of. We brought him in and gave him a long contract because we believed in him. We haven’t forgotten or given up on him.
“It is over to Brandon to provide consistency. We will give him the opportunities and he has certainly taken his last two. Two cameos, but straight away you see that blistering pace. Defenders, certainly up here in Scotland, will find it difficult to cope with that.”