The Blues have made a poor start to the season, losing their first two league games including an opening day home loss to Edinburgh, but O'Halloran warned his side that the Welsh outfit will be all out to arrest their losing streak and put a first blemish on Glasgow's record this season.
Speaking to BBC Scotland, O'Halloran said: "I think they'll be a very, very desperate side.
"We'll probably be favourites in supporters' eyes but we don't want to get complacent.
"It is in games like this that if you take your eye off the ball you get knocked over. It is in front of their fans, who will be expecting a big effort after a couple of losses, and they'll be desperate to deliver, so they will bring a massive amount of physicality.
"We need to match that and be a lot more accurate with our skills so we can maintain the ball for longer periods and dictate the pace of the game."
Finn Russell looks set to feature after an impressive display in the weekend win over Ospreys. It was his first action since playing for Scotland and, briefly, for the British & Irish Lions over the summer.
The stand-off was called into the Lions squad after fine displays for Scotland in the wins over Italy and Australia. He only played for five minutes in New Zealand, his brief cameo coming from the bench after a head injury to starting fly-half Dan Bigger in the 31-31 draw against the Hurricanes.
O'Halloran thinks even that limited involvement will stand him in good stead when it comes to playing his way onto the Lions tour to South Africa in 2021.
"It's four years to the next tour and in terms of his selection as a first five-eighth, he'll be at his very, very best when the next Lions tour comes around," said O'Halloran, who left the Scotland set-up to become Glasgow's attack coach following Vern Cotter's departure from the national side.
"He'll know what is required to be selected. That gives him a goal which is what you need - if you are not striving to get to the next level, it is very often the case that you don't play as well at the level you are currently at."
Summer signing Callum Gibbins impressed on his debut in the back-row, and O'Halloran sees similarities between his playing style and that of fans' favourite Simone Favaro, who left the club in the summer.
"I think they are very similar in terms of their work ethic and their want to be physical and dominate that contact area," the Kiwi explained.
"With Callum you also get a really good awareness of the systems, whereas with Simone you would get times when he would rush out the line and it would either be a big hit or a big line-break for the opposition.
"So Callum's accuracy and the fact that he is a smart guy when we've got so many young loose forwards is really beneficial to the group. He can become a really good mentor to the likes of Matt Smith and Matt Fagerson."