The Scottish club's defence had been stingy so far this season, their 12 tries conceded a RaboDirect PRO12 low.
And Townsend insists the clash at high-flying Leinster is a chance to get back to the basics that have stood them in good stead.
"To lose our unbeaten away record at the Dragons on Sunday was disappointing for a variety of reasons," Townsend told the Glasgow Evening Times.
"But with Saturday's game against champions Leinster at the RDS Arena in Dublin, we have a great opportunity to bounce back.
"We take a lot of pride from being a tough side to beat, but at times against Newport Gwent Dragons our defence wasn't at the required standard.
"We will be looking to get our defensive system working better, much better, on Saturday and the players must put in maximum effort when we don't have the ball.
"Leinster are one of the best attacking sides in Europe, so we're going to have to bring one of our best-ever defensive displays in order to win at the RDS."
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