The Irishman, contesting a partial season with the Korean brand, quickly gelled with the i20 N to chalk up three stage wins that helped the former M-Sport driver into a slender 2.6s advantage.
Breen’s afternoon push helped the 33-year-old snatch the lead from Tanak, who had held sway heading into the midday service. Tanak was however able to respond late on Friday with a first stage win of the season to slash Breen’s lead that had stood at 10.5s.
Hyundai’s Esapekka Lappi will head in to Saturday in third, 11.2s adrift having leapfrogged overnight leader world champion Kalle Rovanpera on Friday’s opening stage.
After struggling for pace across the morning, Elfyn Evans ended the day fourth, 26.5s behind, but ahead of Rovanpera, whose advanced road position contributed to the Finn sliding down the order.
Rovanpera will start Saturday 31.1s behind and is the last factory Toyota in contention after Takamoto Katsuta retired due to damages sustained in a roll in stage 5. Hyundai’s Thierry Neuville and M-Sport’s Pierre-Louis Loubet filled the top seven.
Deep ruts on the first stage of the afternoon, the second pass of Brattby, rendered the test as one that where survival was key.
The conditions appeared to suit Breen as the Hyundai driver produced a blistering time to reach the stage end 7.8s faster than his nearest rival M-Sport’s Pierre-Louis Loubet, who also clicked with tricky road surface.
Breen’s effort was enough to leapfrog Tanak into the overall lead.
"I could probably be the mayor of Brattby at this stage,” said a jubilant Breen. “The car is absolutely on rails - I've never had anything like this before. More of that please.”
Tanak dropped 9.8s to Breen in the test as he came through fourth fastest behind Lappi.
The conditions favoured the latter runners as Rovanpera, first into the test, dropped 21.3s, and emerged slower than WRC2 leader Oliver Solberg and his class rival Emil Lindholm.
"Just before the stage I got a message that traction has left the chat,” smiled Rovanpera. "There was not much I could do - I barely survived the stage but it was really tricky.”
Neuville and Evans were among those just hoping to survive with the former vocal regarding the conditions.
“It is worse than any other year, it is so loose in there and the ruts are very deep, so you just try to survive,” said Neuville, who sustained bodywork damage to the front and rear of his i20 N.
Katsuta was however caught out on the stage as he rolled his GR Yaris after a collision with a snowbank. Luckily he and co-driver Aaron Johnston were able to reach the finish with heavy damage to the front and rear of the car.
The pair reached Stage 6 but were forced to retire due to a leaking radiator that was unable to be fixed, despite stopping at a house on the route to source some water.
At the front, Breen resumed his charge in Stage 6 as the sun began to set, claiming his third stage win of the event. This time he pipped an improving Evans by 2.6s.
Tanak reached the stage end two tenths slower than Evans despite a ragged run, where the Estonian skirted with danger on several occasions.
Rovanpera was able to limit the damage of being first into the test, finishing only 4.3s adrift of Breen.
There was plenty of drama elsewhere as Lappi overshot a junction, which cost him valuable seconds, while Rally1 privateer Lorenzo Bertelli was lucky that a group of spectators were able to push his Toyota out of a deep snowbank.
After showing promise in Stage 5, Loubet suffered a suspected mechanical issue in the front of his Ford Puma that attributed to his 9.6s deficit in the stage.
As darkness fell, Tanak lit up the timing screens to clinch M-Sport’s first stage win of the year, slashing Breen’s overall lead to 6.4s.
The time came despite the Estonian struggling with his tyres as they penetrated through the snow layer and into the gravel road surface underneath.
Lappi maintained his pursuit of the leaders, 0.9s slower than Tanak but 3.2s faster than Breen.
Rovanpera was among the biggest losers on the stage as tyre wear played a part in losing 11.3s to the leaders.
The Finn ended the day in style by winning Stage 7 (Umea Sprint) with a 0.5s margin over Tanak, while Breen dropped 4.3s.
In WRC2, Oliver Solberg leads Sami Pajari by 8.5s.
Rally Sweden continues with a further seven stages on Saturday.
Full results:
| Cla | Driver/Codriver | Total Time | Gap | Interval |
|---|---|---|---|---|
| 1 |
 Craig Breen James Fulton
|
41'26.7 | ||
| 2 |
 Ott Tanak Martin Jarveoja
|
41'37.2 | 10.5 | 10.5 |
| 3 |
 Esapekka Lappi Janne Ferm
|
41'44.0 | 17.3 | 6.8 |
| 4 |
 Elfyn Evans Scott Martin
|
41'52.8 | 26.1 | 8.8 |
| 5 |
Kalle Rovanperä Jonne Halttunen
|
41'54.9 | 28.2 | 2.1 |
| 6 |
 Thierry Neuville Martijn Wydaeghe
|
42'02.0 | 35.3 | 7.1 |
| 7 |
 Pierre-Louis Loubet Nicolas Gilsoul
|
42'19.0 | 52.3 | 17.0 |
| 8 |
 Oliver Solberg Elliott Edmondson
|
43'42.9 | 2'16.2 | 1'23.9 |
| 9 |
Sami Pajari Enni Mälkönen |
43'51.4 | 2'24.7 | 8.5 |
| 10 |
Jari Huttunen Antti Linnaketo
|
44'04.2 | 2'37.5 | 12.8 |
| 11 |
 Nikolay Gryazin Konstantin Aleksandrov
|
44'08.5 | 2'41.8 | 4.3 |
| 12 |
 Ole Christian Veiby Torstein Eriksen
|
44'10.9 | 2'44.2 | 2.4 |
| 13 |
Lauri Joona Tuukka Shemeikka |
44'29.2 | 3'02.5 | 18.3 |
| 14 |
Robert Virves Hugo Magalhaes |
44'34.1 | 3'07.4 | 4.9 |
| 15 |
Georg Linnamae James Morgan
|
44'34.5 | 3'07.8 | 0.4 |
| 16 |
Bruno Bulacia Axel Coronado |
44'45.4 | 3'18.7 | 10.9 |
| 17 |
Fabrizio Zaldivar  Marcelo Der Ohannesian
|
44'48.6 | 3'21.9 | 3.2 |
| 18 |
 Marco Bulacia  Diego Vallejo
|
44'53.6 | 3'26.9 | 5.0 |
| 19 |
 Lorenzo Bertelli Simone Scattolin
|
45'05.1 | 3'38.4 | 11.5 |
| 20 |
Emil Lindholm Reeta Hämäläinen |
45'30.4 | 4'03.7 | 25.3 |
| 21 |
Teemu Suninen Mikko Markkula
|
45'34.8 | 4'08.1 | 4.4 |
| 22 |
Jörgen Jonasson Nicklas Jonasson |
45'56.6 | 4'29.9 | 21.8 |
| 23 |
 Michal Solowow Maciej Baran |
46'01.5 | 4'34.8 | 4.9 |
| 24 |
Egon Kaur Jakko Viilo |
46'24.7 | 4'58.0 | 23.2 |
| 25 |
Roope Korhonen Anssi Viinikka |
46'25.3 | 4'58.6 | 0.6 |
| 26 |
William Creighton Liam Regan |
46'37.7 | 5'11.0 | 12.4 |
| 27 |
Rakan Al-Rashed Dale Moscatt |
47'02.0 | 5'35.3 | 24.3 |
| 28 |
Laurent Pellier Marine Pelamourgues |
47'09.5 | 5'42.8 | 7.5 |
| 29 |
 Ricardo Romagnoli Louis Louka
|
47'29.0 | 6'02.3 | 19.5 |
| 30 |
Diego Jr. Rogelio Penate
|
47'43.6 | 6'16.9 | 14.6 |
| 31 |
Miguel Zaldivar  Jose Diaz
|
47'56.3 | 6'29.6 | 12.7 |
| 32 |
Mauro Miele Luca Beltrame |
48'13.7 | 6'47.0 | 17.4 |
| 33 |
Daniel Alonso Alejandro López Fernández
|
48'26.5 | 6'59.8 | 12.8 |
| 34 |
Joakim Roman Ida Lidebjer-Granberg |
50'27.1 | 9'00.4 | 2'00.6 |
| 35 |
Raúl Hernández Rodrigo Sanjuan |
50'38.5 | 9'11.8 | 11.4 |
| 36 |
Roberto Blach Mauro Barreiro |
50'39.1 | 9'12.4 | 0.6 |
| 37 |
Nao Otake Marko Salminen
|
50'50.8 | 9'24.1 | 11.7 |
| 38 |
Yuki Yamamoto Miika Teiskonen |
50'57.6 | 9'30.9 | 6.8 |
| 39 |
Miguel Díaz-Aboitiz Rodolfo Del |
52'13.9 | 10'47.2 | 1'16.3 |
| 40 |
Tom Rensonnet Loïc Dumont |
52'49.5 | 11'22.8 | 35.6 |
| 41 |
Hamza Anwar Adnan Din |
52'52.2 | 11'25.5 | 2.7 |
| 42 |
Luciano Cobbe Roberto Mometti |
53'50.9 | 12'24.2 | 58.7 |
| 43 |
Alexander Villanueva José Murado |
54'32.3 | 13'05.6 | 41.4 |
| 44 |
Kogure Hikaru Topi Matias |
55'36.2 | 14'09.5 | 1'03.9 |
| 45 |
Jesse Kallio Jussi Lindberg |
1:01'16.8 | 19'50.1 | 5'40.6 |
| View full results | ||||
