The Boys in Blue missed out on the GUINNESS PRO12 top four for the first time in 11 years, as a 25-22 defeat to the welsh club at Rodney Parade effectively ended their play-off chances.
But even worse for Leinster fans was the 16-14 defeat at the RDS two months before, where the unfancied Dragons became the only team to beat them at home since Munster at the Aviva last October.
And while a league double over Leinster may have been rare as hen's teeth in years gone by, Landman insists a repeat performance is not off the table.
"Nick Crosswell got a yellow card in the first few minutes last year, and I thought we couldn't possibly play with 14 men against them," said the 29-year-old South African.
"But we turned things around, our kicking game was great, we left nothing on the pitch, and got the win.
"They won't underestimate us this time, but I think that was the same when they came to Rodney Parade with an even better side than in Dublin and we won again.
"We know it will be a tough game and they will have a strong side even though they are affected by World Cup call-ups. They've got depth and a big budget, but last season gives us confidence."
Newport have made several changes from their 13-0 victory over Zebre in the last round, with full-back Carl Meyer joining wingers Ashton Hewitt and Tom Prydie in the back three.
The rest of the backline remains unchanged, but in the front row hooker Hugh Gustafson comes in for T Rhys Thomas alongside props Boris Stankovich and Brok Harris.
Nick Crosswell also comes in next to Landman in the engine room, while James Thomas and James Benjamin will start in the back row.
Meanwhile, Leinster have made just two changes to their side that beat Cardiff Blues 23-15 at the RDS on their last GUINNESS PRO12 outing.
Marty Moore returns from injury at tighthead prop - his first game since April's Champions Cup game against Toulon - while Isaac Boss makes his first start of the campaign from scrum-half having come off the bench against Edinburgh and Cardiff.
And Dominic Ryan, who lines up at blindside flanker, believes the Boys in Blue will have revenge on the mind and will be hungrier than ever against the Dragons.
"We have more respect for them," he told the Irish Herald. "You also have a bit more venom in that you want to owe them one having been beaten twice by them last season.
"The home game hurt quite a bit. We pride ourselves on winning in The RDS and we lost to the Dragons, who at the time were quite far below us.
"Come the end of the season in a game like that, when you're trying to get into the top four, it could have been the difference especially when you lose by a point.
"I think our set-piece, our line-out and scrum need to be good, as the Dragons have a good scrum when they get it right.
"I think from the first two rounds of the PRO12, we need to get our discipline right. We gave Cardiff 15 points and Edinburgh as well, so we're going to focus big time on it."
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At RDS Arena, 2.30pm. Live on TG4
Referee: Ian Davies (WRU, 34th competition game)
Assistant Referees: Eddie Hagan-O'Connell, Shane Kierans (both IRFU)
Citing Commissioner: John Cole (IRFU)
TMO: Jude Quinn (IRFU)
Leinster Rugby
37 - 13
HT: 20 - 10
Newport Gwent Dragons
3rd October 2015
14:30
RDS Arena
10400
GUINNESS PRO12