"I think it was just nerves getting back into the camp and the full intensity of training", he said.
Coach Justin Langer's call before the game for crowds to show the pair "respect" during this summer does not appear to have registered quite yet.
Paceman Cummins finished with figures of 3-40 and leg spinner Zampa 3-60 as the holders kept the brakes on despite occasional flashes of flair from the Afghans.
And while Mitchell Starc is Australia's best exponent of fast, swing bowling - there's no more risky quick on the planet when he's landing his inswinging yorker - this could well become Pat Cummins' World Cup because of the pace and bounce on display so far. Glenn Maxwell hit the next ball to the boundary to lift Australia to 209-3.
Afghanistan were bowled out for 207 in 38.2 overs with Pat Cummins and Adam Zampa accounting for three wickets apiece.
Afghanistan had won the toss earlier and they made a decision to bat first.
Afghanistan lost both of their openers in the first two overs but rallied with a half-century from Najibullah Zadran and an aggressive cameo from Rashid Khan to creep past 200.
But the move backfired badly, with openers Mohammad Shahzad and Zazai departing for ducks as Afghanistan slipped to five for two in the second over.
Rashid Khan's strike rate of 245.45 is the 2nd highest SR by a batsman against Australia in WC among batsman who have scored a minimum of 25 runs against them.
Tornado seriously injures 3 people in Kansas
Bill Bunting, chief of forecast operations for the NOAA Storm Prediction Center , described the battery of tornadoes as "rare". One of the strongest confirmed tornado this year was an EF4 tornado that killed 23 people in Lee County, Ala .
But those cameos were all too frequent and missing one anchoring innings that may have pushed them closer to a score in the region of 250. Finch got out after scoring a half-century and Warner got a reprieve after Mohammad Shahzad missed an easy stumping, Australia cruise to victory with seven wickets in hand. It was David Warner's 178 and Steve Smith's 95 that sealed the victory that day.
"Adam Zampa got three wickets, but I didn't think he bowled superbly".
"Luckily I got the nod, we're pretty lucky that we've got three pretty good bowlers sitting on the sideline", he added. "They have some very good spinners so if you don't take that into consideration you are playing with fire".
The breakthrough finally came in the 17th over when Finch mistimed a slower ball from Afghan skipper Gulbadin Naib and holed out to Mujeeb Ur Rahman at deep cover.
He said he respected how Smith and Warner handled being treated as villains by the mainly English crowd.
"You've got to give it to the Windies, otherwise they just get on the front foot".
Warner was passed fit to play after recovering from a sore glute. "So that was great for him, to just keep on and do that job really well for us and be not out at the end".
"If we have the sort of audience that we do backing us in the stands, we take a lot of positive things from that".