London Scottish need to complete a hat-trick of victories over rivals London Welsh at the Athletic Ground on Sunday, 2pm kick-off, to keep their hopes of reaching the play-offs alive.
With four rounds of the regular season to go Scottish are nine points off the top four places, and with a visit from leaders Bristol to come on the final weekend it is vital Scottish pick up as many points as they can over the next three weeks.
Scottish's most impressive win of the season to date came against Welsh at the Kassam Stadium on December 21, when a Miles Mantella try and determined rearguard effort saw them beat the then league leaders, 13-5.
Scottish also came out on top (32-26) when the sides met at Monks Lane, Newbury in the first round of the British & Irish Cup, although Welsh did gain revenge with a 21-18 victory in the return leg.
More than 2,500 spectators turned up that day and another big crowd is expected at the Athletic Ground on Mother's Day, as all ladies will be admitted into the ground free of charge.
To stay in the hunt for the play-offs, Scottish still need either Rotherham Titans or Leeds Carnegie to slip up.
Both Yorkshire sides are away at the weekend although their respective trips to Bedford Blues and Nottingham Rugby do not look as foreboding – on paper anyway – as in previous years.
Last year's beaten finalists Bedford are 9th in the table after losing for the 13th time against London Welsh, while Nottingham, who made the play-offs in 2012/13, are a place below the Blues in 10th and are without a win in five games.
Rotherham have won the last three times they have played the Blues in all competitions, but it is seven-and-a-half years and seven games since the Titans last won at Goldington Road in the league.
As for Nottingham, the Green & Whites will be looking to bounce back from a 51-7 beating at the hands of Rotherham in their last home game when they welcome Leeds to Meadow Lane on Sunday.
Nottingham beat Leeds 24-16 on the opening day of the season before Carnegie levelled the series with a 30-19 victory at Headingley over the festive period.
A 25-23 win over relegation rivals Jersey in Round 19 handed Ealing Trailfinders a stay of execution at the foot of the table, although the west London club's task does not get any easier with a trip to GK IPA leaders Bristol Rugby this weekend.
Andy Robinson's men will look to avoid the lacklustre second half performance that saw them fail to score any points after the break for the second game running when they last played the league's cellar dwellers at Vallis Way back in December. Bristol won 21-7.
Jersey will go a long way to securing their place in the division for a third year should they beat Moseley – something they have so far failed to do in the Championship, at St Peter on Saturday. Charlie Hayter scored a splendid hat-trick when Moseley won 31-12 in last season's corresponding fixture.
Cornish Pirates, meanwhile, will be looking to stretch their unbeaten run against Plymouth in league and cup to 10 games in the cross-Tamar derby at Brickfields on Saturday. Prop Jack Andrews' try proved to be the difference last time out, Pirates winning a real war of attrition at the Mennaye Field, 10-3.
Round 20 fixtures
Saturday March 29
Jersey v Moseley, KO 15:00
Plymouth Albion v Cornish Pirates, KO 15:00
Bedford Blues v Rotherham Titans, 17:00
Sunday March 30
London Scottish v London Welsh, KO 14:00
Bristol Rugby v Ealing Trailfinders, KO 15:00
Nottingham Rugby v Leeds Carnegie, KO 15:00