Wales are using Saints as inspiration as they bid to beat Ireland at the Aviva Stadium on Saturday.
Northampton upset the odds to defeat Leinster 18-9 in a Heineken Cup clash in Dublin in December.
It was a stunning performance from Jim Mallinder’s men, who had been hammered 40-7 by the Irish side at Franklin’s Gardens a week earlier.
Saints turned the tables thanks to tries from Jamie Elliott and Wales wing George North.
And North and his Wales team-mates will now look to inflict a similar fate on an Ireland team containing plenty of Leinster stars in the Six Nations showdown this weekend.
“Ireland are a tough team and we just have to be very direct against them,” said Gatland.
“A good example is Northampton’s performance at Leinster, they were embarrassed at home then turned it around in a week.
“It’s a pretty good blueprint about how to play against Ireland. They ran hard, there wasn’t anything flash about it, they just fronted up physically after being blown away.
“They had two good midfielders on that day in Luther Burrell and George North and we’ve got some physicality in our back line, so expect us to be fairly direct.”