Sainsbury's chief executive Justin King has told ITV News that the chain's popular toys range is "new competition" for businesses like Mothercare, whose shares fell 30% today.
Mothercare shares ends day still down 30 percent - haven't recovered from early slump this morning
Shares in Mothercare fell by 30% today after the chain fell victim to fierce Christmas price wars.
Shares in the babycare products chain sank 126p to 294p after confidence in its turnaround plan was hit by today's profits warning.
Mothercare blamed a 9.9% plunge in UK sales on the "highly promotional" nature of the Christmas period and lower footfall.
Sainsbury's enjoyed its busiest trading week ever in the run-up to Christmas, helping like-for-like sales in its latest quarter climb by 0.2%.
Chief executive Justin King said the 14 weeks to January 4 had been a "very tough sales environment" but the supermarket managed to maintain its record of growth - after it was forecast to fall after 35 successive periods of expansion.
Mr King said the seven days prior to Christmas was the group's busiest ever trading week, with more than 28 million transactions.
Waitrose said the strong trading period was driven by growth in online groceries sales, which rose by more than a third in the five weeks to Christmas Eve compared with the same period in 2012.
It said that 619,000 people used their click and collect service in the same five-week period.
Waitrose says it has seen its most successful Christmas on record after sales for the twelve trading days up to December 31 were up 6.5% on last year.
Total sales for the five weeks up to Christmas Eve was 5.4% above the same period in 2012.
It said it also recorded its most successful single day of trading ever after taking £51m on Monday December 23.