Porto have been deducted six points by Portuguese football authorities for attempting to fix league matches.
The league's disciplinary committee ruled that Porto tried to bribe referees in two matches in the 2003/04 season, and, as well as the points deduction, have been fined €150,000 (£119,000) and barred chairman Jorge Pinto da Costa from the bench during matches for two years.
The league's disciplinary committee has also relegated Boavista to the second division and fined the club €180,000 (£143,500) after being found guilty of trying to coerce referees in three games in the 2003/04 season.
The club's chairman at the time, Joao Loureiro, was suspended for four years and fined €25,000 (£19,000).
Leiria, also a top-flight club but unable to avoid relegation this year, were found guilty of trying to bribe match officials the same season and was docked three points while fined €40,000 (£31,000). The club's chairman was suspended for one year.
Five referees have also been suspended for up to six years after being found guilty of corruption.
The sanctions are to take effect within three working days unless appeals were lodged. All three clubs denied the charges.
The points deduction will not prevent Porto from lifting their third consecutive league title, as the club will still maintain a 14-point lead going into Sunday's final fixtures.
The committee's president Ricardo Costa said officials questioned 85 people during the investigation and compiled a case file containing almost 1,000 pages.
He said in a televised press conference: "These decisions were unanimous. Five people agreed with the penalties to be applied."

Latest Sky Sports News Report
Wigan v Burnley - 2nd Half
Sunderland v Birmingham - 2nd Half
Stoke v Tottenham - 1st Half
Everton v Bolton - 1st Half
Portsmouth v Hull - 1st Half
Wigan v Burnley - 1st Half
Sunderland v Birmingham - 1st Half
| Time | Fixture |
|---|---|
| Sunday 21st March | |
| Barclays Premier League | |
| 13:30 | Man Utd vs Liverpool |
| 15:00 | Fulham vs Man City |
| 16:00 | Blackburn vs Chelsea |
| Tuesday 23rd March | |
| Barclays Premier League | |
| 20:00 | West Ham vs Wolverhampton |
| Wednesday 24th March | |
| Barclays Premier League | |
| 19:45 | Aston Villa vs Sunderland |
| 19:45 | Man City vs Everton |
| 19:45 | Portsmouth vs Chelsea |
| 20:00 | Blackburn vs Birmingham |
| Saturday 27th March | |
| Barclays Premier League | |
| 15:00 | Birmingham vs Arsenal |
| 15:00 | Chelsea vs Aston Villa |
| 15:00 | Hull vs Fulham |
| 15:00 | Tottenham vs Portsmouth |
| 15:00 | West Ham vs Stoke |
| 15:00 | Wolverhampton vs Everton |
| 17:30 | Bolton vs Man Utd |
| Sunday 28th March | |
| Barclays Premier League | |
| 12:00 | Burnley vs Blackburn |
| 16:00 | Liverpool vs Sunderland |
| Monday 29th March | |
| Barclays Premier League | |
| 20:00 | Man City vs Wigan |
| Friday 2nd April | |
| Barclays Premier League | |
| 15:00 | Fulham vs Wigan |
| Saturday 3rd April | |
| Barclays Premier League | |
| 12:45 | Man Utd vs Chelsea |
| Time | Result |
|---|---|
| Saturday 20th March | |
| Barclays Premier League | |
| Aston Villa 2 - 2 Wolverhampton | |
| Stoke 1 - 2 Tottenham | |
| Everton 2 - 0 Bolton | |
| Wigan 1 - 0 Burnley | |
| Arsenal 2 - 0 West Ham | |
| Portsmouth 3 - 2 Hull | |
| Sunderland 3 - 1 Birmingham | |
| Tuesday 16th March | |
| Barclays Premier League | |
| Wigan 1 - 2 Aston Villa | |
| Monday 15th March | |
| Barclays Premier League | |
| Liverpool 4 - 1 Portsmouth | |
| Sunday 14th March | |
| Barclays Premier League | |
| Man Utd 3 - 0 Fulham | |
| Sunderland 1 - 1 Man City | |
| Saturday 13th March | |
| Barclays Premier League | |
| Tottenham 3 - 1 Blackburn | |
| Bolton 4 - 0 Wigan | |
| Birmingham 2 - 2 Everton | |
| Stoke 0 - 0 Aston Villa | |
| Chelsea 4 - 1 West Ham | |
| Burnley 1 - 2 Wolverhampton | |
| Hull 1 - 2 Arsenal | |
| Wednesday 10th March | |
| Barclays Premier League | |
| Burnley 1 - 1 Stoke | |
| Tuesday 9th March | |
| Barclays Premier League | |
| Sunderland 4 - 0 Bolton | |
John Barnes looked at the state of Liverpool on Goals on Sunday - and tipped them to finish fourth.
Pictures from Saturday's Premier League action where Arsenal out-muscle West Ham to go top.
Peter Fraser meets Dirk Kuyt to talk about Liverpool, facing Manchester Utd and going to the World Cup.
Arsenal beat West Ham to go top of the table, Iain Dowie started his Hull City reign with a dramatic defeat and Spurs tightened their grip on fourth.
Follow all of Sunday's action, including minute-by-minute updates on the crucial Premier League games with skysports.com's Score Centre.
Struggling Darlington have sacked manager Steve Staunton after falling 19 points shy of safety.
West Ham co-owner David Gold wants to launch an ambitious bid to bring David Beckham to the club.
Portsmouth fans will have to wait to discover the identity of the main investor considering a takeover.