The sides go head to head in three 50-over contests at Stormont next week, starting today when the hosts will be looking to avenge a 2-0 defeat in the T20 leg of the tour.
Rashid was a predictably central performer in the sprint format, living up to his world number one status with combined figures of seven for 52.
The teenage leg-spinner could hold the key once more and will have 10 overs rather than four to weave his spells on the Irish - and Porterfield acknowledges how crucial their response will be.
“He’s a very good bowler, he’s right up there at the top of both formats for a reason,” he said.
“The more you play against someone the more you get to deal (with them), you’ve got to evolve your game and play him well, just as he keeps looking to evolve his.
“If, come the end, he hasn’t hadn’t a successful week in the end column then I think we will have had a successful week.
“The top order has to perform, it’s our job to put a total on the board.
“If you expose the tail to Rashid he’s going to have one over on them, but if we minimise the wickets he gets in that top seven then a lot of games we’ll come out on top.” he added.
The sides last met in the ODI format in March, at the final of the ICC World Cup qualifier in Harare.
On that occasion Afghanistan were again victorious, pipping their opponents to a place at next summer’s tournament in England.
They also sit two places above Ireland in the ODI table, 10th versus 12th, but Porterfield is far from pessimistic.
“We have a lot of confidence, we’ve played a lot against Afghanistan in this format in our own conditions and come out on top,” he said.
“The longer format has probably suited us for whatever reason over the last couple of years. We haven’t been able to put it together in T20s but 50 overs and the longer format we have been able.
“If we can hit the ground running it makes the week a hell of a lot easier rather than coming from behind.”