Harper has been one of the most prodigious professionals in the league's history but despite scoring 8,600 runs and taking 610 wickets for Bacup never tasted title glory at Lanehead.
Now in his first season with Nelson, the West Indies' all-rounder will be a fairly safe bet for a winner's medal if the league leaders beat their nearest challengers at Seedhill.
Victory could open up a 31-point gap with four games to play and captain Duncan Spencer, who hands the reigns over to Harper, admits the club faces a potentially decisive weekend with a local derby at Colne to follow on Sunday.
Spencer, who is getting married tomorrow so misses the weekend games, said: ``I would not say it would put us over the line but if we could win both games and East Lancashire are beaten by Todmorden on Sunday as well it could be mathematically possible that we have won it.
``But it's difficult with so many points to play for and if they beat us they could be only seven points behind.''
The onus is therefore clearly on East Lancs to force a win.
``The draw would suit us better and if I was in Mark Lomas's shoes I would have to play to beat us really. ``I don't think we will go into the game negatively though. We will play positively like we have all season and hopefully that will pay off by Saturday night,'' Spencer added.
Nelson have won 10 of their 21 games with Harper the key figure thanks to his 85 wickets and 661 runs as the club chases its first title since 1994.
``I would be the first to acknowledge that but there are 10 other guys who have played their part as well,'' said Spencer.
Left-arm seamer Danny Kegg has picked up 25 wickets and Paul Garraghty is second in the league batting averages to underline the support Harper has had.
East Lancashire, who have lost stand-in professional Paul Ridgway to Lancashire for their championship clash at Durham, will have another Lancashire player, opening batsman Mark Chilton on duty.
They know they need maximum points to have any chance of adding the league title to their Worsley Cup success in what could be skipper Lomas's last season at Alexandra Meadows. Lomas, who passed 500 runs for the season with 89 against Haslingden last weekend, has expressed a desire in getting a professional's post in the Ribblesdale League.
``If somebody asks me to pro I would be interested,'' said Lomas who has played Lancashire second team cricket this season.
``I have taken East Lancashire as far as I can and turned them into as professional an outfit as I can. I am sure I have got the ability to help another side improve. If Mark and Jonathan Harvey can do it I am sure I can.'' Former Lancashire captain Mike Watkinson will again deputise for Enfield at Bacup.
Fixtures: Accrington v Ramsbottom, Bacup v Enfield, Haslingden v Burnley, Lowerhouse v Church, Nelson v East Lancs, Rishton v Rawtenstall, Todmorden v Colne.