While Dan Parks seemed undroppable after a brilliant 2010, the Cardiff and former Warriors fly-half now finds his position under threat after two under-par displays.
And after Glasgow coach Sean Lineen opted to leave out teenager Duncan Weir for the trip to Galway, Jackson is happy to be battling for a starting berth on two fronts heading into Scotland's RBS 6 Nations clash with Ireland.
He said: "It's great to see Dunky back and that gives me an added push. I've got one eye over the shoulder and I hope Dan has felt the same pressure from me in training.
"I've just got to concentrate on my own performance and, hopefully, play my way into contention. It is at the back of my mind."
Lineen added: ""It's great to have Ruaridh back because he's been playing so well for us.
"Obviously Duncan had a solid game last weekend so it's fantastic to have both young 10s back together and battling it out."