The Danish frontman scored in the first half at Queens Park Rangers, running on to a through ball from Sean Maguire.
Riis has got four in the Championship and the same number in Carabao Cup action, and you have to fancy him to get a decent way into double figures.
Riis joined North End on October 1 last year from Randers FC for £1.2m.
His debut came three days later as a substitute in the 4-2 win at Brentford.
He had to wait until his fifth start and seventh game in all, to get off the mark, that coming in a 3-0 win at Reading on November 4.
Riis was to finish last season with only three goals – two in the league and one in the FA Cup.
This season’s statistics show that there has been a clear improvement in his game, no doubt helped by a consistent run in the team.
He has started nine games on the bounce, the win at Morecambe when he scored twice kicking off that run.
For the last seven league games, Riis has had Sean Maguire starting alongside him in the attack. They do work well off one another, although no league goals yet for Maguire this season will see fingers pointed.
Maguire set up both of PNE goals at QPR but later in the game was to limp off with a hamstring injury.
Whether the injury was minor enough to recover from during the international break, remains to be seen.
If Maguire takes a little longer, it will be interesting to see who partners Riis when action resumes against Derby County.