The ex-dual code England international gets his first taste of the city rivalry when Rovers host Lee Radford’s side tonight.
Second-row Tomkins, 31, spent more than 10 years in Wigan colours over two spells so experienced plenty of derby clashes with fierce foes St Helens.
Asked which he thought was the biggest, he said: “They’re probably as big as each other but I think there’s extra with this one.
“It’s one city – it’s either side of the city whereas Wigan and St Helens are different towns – so in that sense this is probably bigger.
“I’ve not played in one yet so it is something I’m really excited about. I don’t think it will be too dissimilar to Wigan/Saints, so that sets me in good stead for this as it won’t come as too much of a surprise with the atmosphere which I’m expecting to be huge, especially in round one.”
Tomkins left Wigan under a cloud last June following an off-field discretion but quickly had a positive impact with Rovers. So much so that, as Shaun Lunt continues his recovery from serious illness, he was named captain.
“I did it a couple of times at Wigan when Lockers (Sean O’Loughlin) wasn’t playing but not very often,” said Tomkins.
“It’s a massive privilege here and very humbling as it was voted for by the players. It’s probably a reward for working hard since coming into the club and trying to have a positive impact.”
Head coach Tim Sheens will look to Tomkins to lead from the front and bring all his experience to bear as Rovers seek to win a home fixture against their rivals for the first time in five years.
On his own aims, he said: “I wouldn’t say I was playing at my very best last season but I’m going on 32 and probably not the same player I was at 24, 25.
“But I have different strengths now and probably looking for the same as what we all want as a club – some consistency.”
Wigan’s nightmare 24 hours was completed last night as they went down 22-12 to St Helens.
The reigning champions failed to win back the two points they were deducted for a salary cap breach on Wednesday.