Aldi and Lidl dramatically increased their market share over the Christmas period as £1 in every £14 in grocery spending went to the discount retailers.
The two brands took a 7.1% share over the 12 weeks to January 5 compared to 5.8% the year before, with Aldi increasing total sales to more than £1 billion.
Data from Kantar Worldpanel confirmed Morrisons as the big loser in the sector as it was the only business to see a fall in total sales. Its delay in launching an online operation saw it miss out on a web ordering surge that propped up its rivals.
Total grocery sales were up 2.9% but Waitrose again showed its success in luring higher-spending shoppers by beating the figure with a 6.4% improvement and taking its market share 0.1% higher to 4.8%.
Tesco and Sainsbury's also muscled in on the premium market as their Finest and Taste the Difference brands strongly outperformed their value ranges. The two retailers were also buoyed by double-digit growth in their convenience stores.
Of the big four grocers, only Sainsbury's held its own in market share, which remained at 17.1% and helped it draw neck-and-neck in the rivalry to be Britain's second biggest supermarket with Asda, which saw its slice fall from 17.5% to 17.1%.
Tesco, still the largest by a distance, fell from 30.4% to 29.6% as it managed only a 0.2% increase in sales.
But Morrisons dipped from 12% to 11.5% as total sales fell by 1%.
The Bradford-based retailer, which launched its online deliveries just days ago, missed out on the UK's 22% increase in internet grocery sales over the period, with 15% of households placing orders.
Meanwhile, Aldi's market share climbed by nearly a third from 3.1% to 4% as sales rose 29.4% to £1.08 billion in the period. Lidl's share increased from 2.7% to 3.1%, with revenues up 17.5% to £528 million.
The data also indicated an easing in pressures on household budgets with grocery price inflation standing at 2.5%, the lowest since October 2012.
Edward Garner, director at Kantar Worldpanel, said: "Among the big four, only Sainsbury's was able to resist the relentless pressure from the discounters and Waitrose.
"Now catching up with Asda, it managed to hold share and out-perform the market with year-on-year growth of 3.1%.
"As revealed last week, Morrisons suffered the most among the major supermarkets with its share dropping from 12% last year to 11.5% now and a decline in overall sales of 1.0%.
"The absence of an online offering is a major factor in its decline with total internet grocery sales over the Christmas / New Year period growing at 22% with 15% of British households placing orders.
"However, the retailer has now begun deliveries via Ocado in the Midlands which might help it return to growth."