The one that springs to mind for me is atomic kitten's whole again. It was the fifth release from their debut album, following peaks of 10, 6, 10 and 20 I think. None of the other tracks passed 200k but, as we all know, whole again has to date sold over a million! It was also the track which gave them a future as, iirc, they were about to be dropped by their record company who weren't happy with their lacklustre performance in the charts to that point.

 

Another biggie iis Robbie Williams' angels. The fourth release from his debut album, again this was the track which effectively launched his career. It followed peaks of 2, 8 and 14 I think, making number 4 in early 1998, but has sold well over a million now.

'Thrift Shop' by Macklemore & Ryan Lewis was the fifth release from 'The Heist' and was a hit ALL over the world, their signature hit, solidified them as big chart contenders and has sold millions of copies worldwide. 'Cant Hold Us' 'Wing$' and 'Same Love' and another song were released before 'Thrift Shop'.

Another one that springs to mind: 'Porcelain' was the sixth UK single from Moby's Play album, but the only one to go Top 10.

'Everything Changes' by Take That was the fifth single to be released from the album of the same name.

How could we forget Nicki Minaj and Super Bass! The 6th single from Pink Friday to reach the UK top 100, the 4th to reach top 40 and the 1st to reach top 10

It wasn't on the original Pink Friday though

It wasn't on the original Pink Friday though

 

It was on the iTunes version.

Thanks for correcting me! Bought the physical copy myself because of Super Bass and the re-release.