The 31-year-old hooker is set to feature on the trip to London Scottish as Carnegie return to the Championship after a fortnight in the British & Irish Cup.
Having debuted in 2006, Nilsen stands on 199 games with only club legend Mike Shelley – the prop who lifted the Powergen Cup for Leeds Tykes at Twickenham the year previously – above him on a record 244 appearances and fellow hooker Rob Rawlinson who pulled on the jersey 209 times.
Nilsen, who joined Leeds at the age of just 17, could surpass the latter’s total later this season but first he is looking forward to this significant milestone.
Asked about his debut, he recalled: “It was Cornish Pirates at home and although I was named as replacement hooker I came on as a back-row and it was under Stuart Lancaster.
“I’ve been aware this has been coming up as my old man keeps an eye on it on the website.
“I’ve been here a long time now, since I was 17 and I’m nearly 32 now. But I’m looking forward to Scottish, my 200th appearance and hopefully getting us another five points.”
Second-placed Carnegie hope to do that to keep in touch with leaders London Irish who they will also play in the B&I Cup quarter-finals at the Madejski Stadium in March.
A product of the club’s famous academy, Manchester-born Nilsen has played 11 games this term, starting seven and scoring one try. On the matches that stand out during his 11-year first-team career, he replied: “There’s a few.
“Your first game for the club always sticks out but others also for the right and wrong reasons.
“I remember being away at Otley and we got a phone call saying we’d won promotion.
“There was the home game v Worcester when we avoided relegation but also the match at Northampton when we lost by a point (and went down) knowing we could have stayed up.”
Dougie Flockhart reached his own double century for Doncaster Knights last week and so makes his 201st appearance as they head to Bedford Blues today.
The winger/centre actually debuted for the South Yorkshire club against Bedford and said: “It’s never an easy game down there. We both play a reasonably wide style but often, when we play each other, there’s not actually many tries.
“It’s always a close-run game between the pair of us and there’s been a few times where we’ve nicked it in the last few minutes.
“They were one of our main rivals last season and, though they haven’t gone as well, they look a better side than their position (ninth) suggests.”
Doncaster, last season’s beaten Championship finalists, sit third and Flockhart said: “We’re in a good spot to push on for the play-offs again. We always like playing Yorkshire and maybe we could get to the final and give Irish a good run for their money, going one better than last year.”