Group like-for-like sales in the 19 weeks to January 9 rose 0.4%, its first reported increase for more than four years.
The beleaguered supermarket chain said group like-for-like sales in the six weeks to January 9 gained 2.1%.
Within that, UK like-for-like sales increased 1.3% and international like-for-likes lifted 4.1%.
In the third quarter to November 28, group like-for-like sales fell 0.5% and the UK fell 1.5%, but international sales rose 2.9%.
Under new chief executive Dave Lewis, Tesco has been reducing reliance on voucher promotions and cutting prices on a range of basic groceries instead.
The group blamed the fall in UK third quarter like-for-like sales partly on the impact of not repeating three '£5 off £40' national coupon campaigns from the previous year.
Lewis said: "Our Christmas performance was strong, benefiting from lower prices.
"There is plenty more to do, but we are making good progress and are trading in line with profit expectations for the full year."