Having defeated the Old Boys twice in Coca-Cola Combination Division II and in the JFA’s Charity Cup final, Portuguese twice came from behind to score four late goals to win 7-3 at Les Quennevais to complete their fourth victory.
Kamil Adamczuk and Joao Mendonca both scored twice with Freddy Mendes, Manny Fernandes and Carlos Carolo adding singles.
John Jefferson, Jamie Shaw and Andy McKnight netted for Beeches.
St Lawrence beat St Martin/SCF for the second time in a month, 2-1 at St Lawrence where Steve Mitchell and Mike Donoghue put the hosts two-up before Michael Nelson hit a late consolation for the travellers.
Jersey Nomads cruised to a 5-0 success at the FB Fields against St John while St Brelade won by the odd-goal in three against Sporting Academics at Les Quennevais.
Ben Doherty (two), Paul Lees (two) and Ged O’Donoghue registered for 2005 cup winners Nomads; Nick Azern and Dave Fitton for St Brelade and Ben Gallichan, with his 15th goal of the campaign, for Accies.
The semi-finals are at Les Quennevais on Saturday 3 March, St Lawrence face Portuguese while Nomads oppose St Brelade.
Grouville opened a four-point advantage at the top of Division I Reserves, from a game played more, following a 2-1 win against Sporting Academics at Le Boulivot.
Nelio Maroté and Darren Quintal were on target for the hosts and Ged Horgan for the visitors.
St Ouen made it 14 matches unbeaten this season, ten in the league and four in two cup competitions, with a 6-3 win at St Martin/SCF to replace the team they beat to go top of Division II Reserves.
The winners, who have two games in hand, lead on goal-difference following a brace by Jon Evans and singles from Shane Carré, Scott Samson, Callum Duffy and Jason Andrade.
Aaron Vetier, Matt Polglase and Pascal Corcoran scored for St Martin/SCF.
St John completed a divisional double over the Portuguese Club, 3-0 at home after goals by John Michel, Jerry Vieira and Lance Guille, the latter who was later sent off following the alleged use of foul and abusive language.
The top two in Division C both won, leaders St Brelade 3-1 at St Clement and Jersey Wanderers 7-1 at FB Fields against Sporting Academics.
St Brelade, who have won nine league games on the bounce since losing their opener 6-2 at Grouville last August, were on target through Tony Barnes, Nathan Hadley and Mark Walker.
Jason dos Santos replied with a penalty.
Kyle Riddell bagged a hat-trick and Martin Le Guyader, Scott Young and junior Luke Campbell one apiece for Wanderers, their other goal was an own goal, with Dave Harrison converting Accies’ consolation.