Tottenham's European hopes were dealt a major blow as they went down 2-1 to Aston Villa, increasing the possibility of a first season without continental football since 2010 or, perhaps worse, a place in the Europa Conference League.
A neat finish by Jacob Ramsey and Douglas Luiz's 25-yard free-kick earned Villa a deserved victory, which moved them level on points with sixth-placed Spurs with two games to play; Brighton are just two points behind both with three, albeit tricky, games in hand.
Spurs, who scored a late consolation through Harry Kane's 90th-minute penalty, can take comfort in Villa's trickier run-in, with Unai Emery's side still to visit Liverpool and host the Seagulls (in what could be a play-off for Europe), while they face Brentford at home and a trip to Leeds on the final day.
Regardless, this was another difficult afternoon in a season that many Spurs fans are desperate to end, which went a long way to demonstrating the benefits of stability and good coaching.
Villa were 14 points behind Spurs when Emery was appointed in October but have now completed the double over the north Londoners, and boasts five more victories in the top-flight in that period.
The Spaniard has transformed the Villains and it showed on the day, with the hosts looking like a side who had been playing under a top coach for seven months and a disjointed Spurs looking every inch a team who are playing under their third head coach since March.
When the visitors did threaten to get behind Villa's high-line, Heung-min Son and Richarlison were unable to beat the offside trap and their fleeting moments of promise all ended with a linesman's flag, including a late equaliser from the Korean, which was ruled out.
Ultimately, the defeat will probably decrease Mason's chances of landing the permanent head coach's job, although the 31-year-old is hardly to blame for the side's historic failings, which long pre-date his panicked appointment.
This result means Spurs are still without a win on the road since January and they last won outside of London in October, a damning statistic for a club with their quality and ambitions.
They also continued a pattern of conceding early on the road, shipping inside the first eight minutes for the third straight match away from home. Even a trip to Elland Road on the final day appears daunting at present.
Were it not for Kane, who has now scored 27 Premier League goals this season, it is shuddering to think where Spurs would be in the table, although the England captain showed he is only human by missing their best chance from open play at 1-0, firing straight at Emi Martinez after good pressing from Pierre-Emile Hojbjerg.
Kane still salvaged something for Spurs, winning and converting a penalty after being caught by the goalkeeper following a burst into the box.
It says something about how rapidly Spurs' ambitions have deteriorated over the course of the season that their late consolation could yet prove hugely important in scraping a European spot, since it maintained a plus-two goal difference over Villa.