'Defence is going to be massive' as Saints host Harlequins
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It will be a clash of the wounded sides at cinch Stadium at Franklin's Gardens after both were beaten on derby-day weekend in the Gallagher Premiership.
Saints suffered a disappointing 26-17 defeat at Leicester Tigers while Harlequins were beaten 38-10 in their home clash with Saracens.
Ludlam is desperate to help his team bounce back, but he is well aware of the threats free-flowing Quins can pose.
"It's where our defence has really got to come to the party," Ludlam said.
"We've seen an improvement in our defence this season and against a team like Quins, who are super-hot and going to test you mentally for 80 minutes, it's about our ability to stay in it.
"Those penalties that we're talking about comes down to our control and our ability to want to defend for long periods of time and have confidence that we can.
"Defence is going to be massive this week."
Saints know plenty of lessons must be learned from the loss at Leicester.
Ludlam said: "We need to look at that first half. They caused our breakdown too many issues and didn't allow us to apply pressure for long periods of time.
"You see in the last 15, 20 minutes how when we do get our breakdown right we can put a lot of pressure on teams, win pens and make breaks from them - we just didn't do it quickly enough.
"The way we play, our shape is obviously a little bit wider, which leaves us a little bit prone to those inside competes. Tommy Reffell is one of the best in the Premiership at it and he caused us way too many issues.
"When the weather's like that, we probably need to tighten our game up a little bit more and give that inside man a bit of a better opportunity to give us some good ball.
"It's just an adaptation thing and we need to fix it.
"The positive thing was that we were still well in the game even though we felt like we hadn't fired a shot.
"In terms of intent, I thanked the boys because the intent was there but we were just missing that element of control."
The outcome didn't dampen Ludlam's enjoyment of derby day.
He said: "I loved it.
"We've been wanting a battle all week and we said going away from home to Welford Road, we've got to expect a battle.
"These are the ones as a team you get remembered, they're the ones we really find out what we mean to each other so I was buzzing out there.
"I loved the intent the boys showed, it's just a shame our control went out the window a little bit."