Kim Little hit the all-important winner as Arsenal beat Everton 1-0 to put themselves in pole position to lift the Women's Super League title.
The midfielder's strike sent the Gunners a point clear of Birmingham and both side have only one match left.
Lincoln climbed to fourth, four points behind third-placed Everton, with a 3-0 victory at Doncaster Belles.
Bristol Academy's 1-0 win at Chelsea - Helen Bleazard scoring - lifted them to fifth spot as Blues dropped to sixth.
Arsenal 1-0 Everton
Everton made the livelier start and after just five minutes midfielder Fara Williams forced goalkeeper Emma Byrne into a diving save from a 25-yard free-kick.
As Arsenal hit back, both winger Rachel Yankey and Little had long-range efforts kept out by Rachel Brown, though neither shot troubled the keeper.
Brown dived in vain, however, when Little's powerfully struck 20-yard shot flew just inside the near post to break the deadlock.
The visitors responded well and only a fine goal-line save by Byrne from striker Natasha Dowie, following a 65th-minute Williams corner, prevented an equaliser.
Byrne then had to go down at her near post to keep out a low cross-shot by Williams 10 minutes from time.
But the Gunners held on to go top for the first time since their opening-day victory over Chelsea, Birmingham having headed the table in the meantime.
On the final day of the season Birmingham will meet Doncaster Belles while Arsenal travel to bottom-of-the-table Liverpool.
Doncaster Rovers Belles 0-3 Lincoln
Striker Lucy Staniforth put Lincoln in front with a curling 23rd-minute shot that sailed into the top corner of the net.
Right winger Jess Clarke squeezed in a narrow-angle 75th-minute effort to double the visitors' advantage.
And eight minutes from time Clarke crossed for midfielder Bonnie Horwood to complete the scoring with a near post header.
Chelsea 0-1 Bristol Academy
Bleazard raced through the Chelsea defence to shoot home from 20 yards for what proved the winning goal.
The home side had chances to equalise, but Kate Longhurst and Helen Lander failed to find a finishing touch and Bristol ran out worthy winners.