The Queen visited a replica of the first Sainsbury's shop to mark the chain's 150th anniversary.
“This was a record-breaking Easter for Aldi," says chief executive Giles Hurley, reacting to the figures which show a gain in market share for Aldi in the first 12 weeks of the year.
"Our Hot Cross Buns proved particularly popular, selling more than two million a week in the run-up to the holiday," he adds.
“This strong Easter trading period, following our best-ever Christmas, shows that Aldi is increasingly becoming the supermarket of choice for key seasonal events."
Sainsbury's has regained its place as the UK's second largest supermarket from Asda, according to the latest market data from research from Kantar.
The two chains - who saw their attempt to merge scuppered last week by the UK's competition authority - have been neck-and-neck for some time.
Last month, Asda overtook Sainsbury's. However, Kantar say Sainsbury's has now reclaimed second slot with a 15.4% share in 12 weeks to 21 April, compared with Asda's 15.2%.
The discount chains remain a threat however, with Lidl’s market share hitting a new high of 5.7%,
Overall it was a good period for the grocery sector, Kantar said. Total year-on-year sales increased by 2% during the period, helped by a "record-breaking" £2.5bn spent during the Easter week.
The competition watchdog blocks the Sainsbury's-Asda merger, warning it would leave consumers worse off.