Manager Brendan Rodgers reckons Celtic got a taste of things to come from Jonny Hayes after watching the Irishman open his Hoops account on Saturday.
The £1.3million capture from Aberdeen netted his first goal for his new club during the 9-0 romp over Shamrock Rovers.
And Rodgers reckons the Dubliner showed plenty to be excited about on his return to his home city.
He told CelticTV: "When you're an attacking player and come to your new club it's important to get off the mark early.
"He has settled in very well off the field. He is a good guy, a mature guy, and he has mixed in really well over the last couple of weeks.
"We don't need to rush him but he's going to make a big contribution to the squad and you saw that today in the half hour he was on, when he showed his pace and his crossing ability. He has an eye for a goal.
"He got his goal and that will make him happy and he can continue to build on that throughout the season."
Celtic sent out an ominous warning to Linfield ahead of next Friday's Champions League qualifier in Belfast as they ran riot at the Tallaght Stadium.
Stuart Armstrong and Scott Sinclair helped themselves to doubles, while Hayes, Mikael Lustig, Moussa Dembele, James Forrest and Tom Rogic also found the net.
And Rodgers was delighted to see his team in such ruthless form.
"It's the identity of trademark of the team which we have created," he said.
"They never relaxed and kept working. I thought defensively, fundamentally, we were very good in terms of our pressing.
"These are the games where you are building up that element of fitness to go and press and get on the ball, and then from that our quality came through.
"We were very good in some of our play and some of the goals we scored. It was very pleasing. It was only our fourth game (of pre-season) but I can see the development in how the team is building up."