Mumba came off the bench to turn the game after Zambia had battled to break down a stubborn Malawi in their Group A clash.
Zambia failed to get out of the pool stages last year despite home advantage but have made a powerful start to the 2018 campaign with just the pool winners and the best-placed runner-up advancing to the semifinals.
It was a tense first half that produced little in the way of chances for either side.
The breakthrough for Zambia finally came on 63 minutes when Oliver Lumbiya’s cross was headed into the path of substitute Prince Mumba and he provided a neat finish, much to the delight of the home crowd.
It was 2-0 with five minutes to play when Zambia captain Edward Chilufya fed the ball through for the bustling Mumba, who got goal-side of his defender and slipped the ball into the back of the net.
Lesotho and Angola kicked off the tournament with an entertaining opening match that ended 1-1.
Lesotho largely dominated the fixture, especially in the first half, as they created numerous opportunities, most centered around lively forward Tseliso Botsane.
It was the bustling number nine who opened the scoring on nine minutes with a well-taken goal that gave last year’s beaten finalists a deserved lead.
Botsane’s pace was causing the Angolan defence all sorts of trouble and he found space almost at will, and from one such foray forward provided a teasing cross for Bonang Mohapi, who missed his kick with just the goalkeeper to beat.
Angola came more into the game in the second period and grabbed an equalizer through substitute Daniel Liberal, who had only been on the pitch two minutes when he headed home a corner.
Liberal almost found a winner too when his shot from 25-yards flashed just wide of the Lesotho goal and the spoils were shared.
Monday’s matches will be two eagerly anticipated affairs as Zimbabwe take on Group C rivals Botswana at the Nkana Stadium at 12pm (10am GMT) and South Africa play Mauritius at the same venue at 3.30pm (1.30pm GMT).
Zimbabwe have not performed well by their own high standards in recent Under-20 championships and will be desperate to add to their six titles at this age-group level. They come up against a dangerous Botswana side who have the ability to surprise, but with Lesotho and Angola having drawn their opener in this pool, it is a chance for one of these sides to take charge of the group.
Defending champions South Africa will be hoping for a bright start against Mauritius with the pool having cut to three teams following the late withdrawal of Namibia.
With just the top team in the group likely to advance to the semifinals, any slip-ups from either side could prove costly.
Sunday’s results
Group C
Lesotho 1 (Botsane 9) Angola 1 (Liberal 64’)
Group A
Malawi 0 Zambia 2 (Mumba 63’, 86’)
MONDAY’S FIXTURES
Group C
12pm (10am GMT): Zimbabwe vs Botswana – Nkana Stadium
Group B
3.30pm (1.30pm GMT): South Africa vs Mauritius – Nkana Stadium
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