On December 18 Popov was appointed Commander of the 61st Army (Bryansk Front) and fought well during the counteroffensive.

In 1943 firstly he commanded a larger mechanized group, but in February his unit was badly defeated.

Then he was appointed Commander of the Bryansk Front (5 June – 10 October 1943), with which he participated in the Battle of Kursk.

He was demoted to Colonel General (20 April 1944) because of the unsuccessful actions in the Baltic area, but the real reason seems to be his criticism on Nikolai Bulganin, who was Commissar at the front.

On 7 May 1965, he was subsequently honored with the title Hero of the Soviet Union for his services during World War II.

He died on 22 April 1969 from an accidental fire at home and was buried in Moscow's Novodevichy Cemetery.