England winger Ryan Hall marked his 300th appearance for Leeds Rhinos with a crucial try to help get them back on course for a home semi-final.
The Rhinos turned around an 8-2 half-time deficit to gain a tense 16-14 victory over St Helens on the night the club bade a fond farewell to the famous South Stand, which is to be demolished as part of a major Headingley stadium redevelopment.
It means Leeds are three points clear of third-placed Hull FC with four matches left of the Super 8s, while St Helens missed the chance to climb back into the top four.
Just two points separated the two sides in their meetings in the regular season and there was once more little to choose between them.
After Mark Percival and Kallum Watkins traded penalties in a nervy opening, Jonny Lomax crossed just before the break to put Saints in control.
But Leeds, who were thrashed at Wakefield Trinity last week, fought back with tries from Hall and Adam Cuthbertson and then held off a late Saints charge after Danny Richardson's try to celebrate one last win in front of the South Stand.
Leeds head coach Brian McDermott said: "I've never not been proud of our players but I'm just extremely proud to be their coach tonight. I don't know where we got that second half from.
"I thought Saints were great. They were beating us off the deck consistently in the first half and we never got a grip of their quick play-the-balls. We made far too many errors in the first half and I thought it would have taken too much juice out of us.
"We didn't change anything tactically for the second half, we just had to go out and roll our sleeves up and they did that right up to the final whistle.
"You might argue we should have executed better and I agree but I thought it was a great game of rugby league between two teams who were committed as anything. They were great defensively, we found it really hard to break them down.
"The win has given us a big boost for second spot. We've still a bit of work to do but it gives us a bit of breathing space.
"We're not guaranteed top four yet and I think the games will get tougher. The bar will need to be raised."
Saints head coach Justin Holbrook said: "I couldn't be prouder of my team. Unfortunately that's two weeks in a row we've been beaten by two points.
"I don't think we played poorly. We didn't have much ball in the second half. We were camped in our own half. But we got within two points away from home against a very tough side.
"We just couldn't get going for one reason or another in the second half but full credit to Leeds, they played very well."
Holbrook confirmed Australian signing Ben Barba will make his debut in Saints' next game against Wigan Warriors in a fortnight's time after completing a 12-match ban.
"He's been training very well for a while now," Holbrook said. "It will be good to get him out there."