Striker Muhammad Shaban scored a brace as East African guests Uganda stunned holders and hosts Zambia 2-0 in their Group A opener at the 2017 Mopani Copper Mines COSAFA Under-20 Championships in Kitwe on Wednesday.
Uganda were deserved winners over the African champions, who have a new-look side this year as they build towards the defence of their title in the 2019 African Youth Championships.
The Young Chipolopolo certainly had their chances, but were undone by Shaban's double-strike in the second half at the Arthur Davies Stadium.
Zambia came close to the opener when captain Prince Mumba saw his shot cannon back off the woodwork, before Lameck Banda was denied by a fine stop from Uganda keeper Keni Saidi.
The East Africans were ahead six minutes into the second period when Shaban netted from a tight angle after turning home Steven Mukyala's cross to stun the sizeable home crowd.
The Kampala City Council forward doubled his side's lead three minutes later with another neat finish.
Zambia had goalkeeper Daniel Sikanyika to thank as he denied Stephen Mukwala as Uganda pushed for a third, while the visitors also had a goal disallowed in what was an accomplished performance from them that will elevate them to one of the tournament favourites.
In the other fixture in Group A, Malawi edged Swaziland in a five-goal thriller with a 3-2 victory as Patrick Phiri bagged a brace of goals.
Highly-rated Peter Banda put the Young Flames ahead as he drilled the ball into the back of the net, before he then blasted the ball over and saw another fine effort saved by Swaziland goalkeeper Mlamuli Lukhele.
Swaziland were brighter at the start of the second period and equalised through Nuno Tsabedze.
Phiri put Malawi ahead three minutes later, but Swaziland were level again before the hour-mark when Order Mamba converted a penalty.
However, the Young Flames had the last laugh as Phiri headed home after Banda's free-kick had come back off the crossbar. North African guests Egypt got their tournament off to a winning start in a hard-fought 1-0 success over Mozambique.
Hussein Abdelkader grabbed the only goal of the game four minutes from time for what turned out to be a deserved victory for the Young Pharaohs.
The second match in Group B will be played on Thursday when South Africa take on Mauritius at the Nkana Stadium (kick-off: 15h00 local; 13h00 GMT).
South Africa are determined to regain the title they lost to Zambia on home soil last year and have a new batch of young stars working under coach Thabo Senong. The first match in Group C will be played before that as regional powerhouse Zimbabwe take on Lesotho at the same venue (kick-off 12h00 local; 10h00 GMT).
Zimbabwe were desperately disappointed with their first round exit 12 months ago, and will be hopeful of adding to their six regional titles this year.
The other two teams in that pool are Angola and Namibia, who meet on Friday.
Only the top team in each pool and the best runner-up advance to the semifinals that will be played on December 14.
Group A Swaziland 2 (Tsabedze 53', Mamba 59') Malawi 3 (Banda 12', Phiri 55', 65') Zambia 0 Uganda 2 (Shaban 51', 54')
Group B Mozambique 0 Egypt 1 (Abdelkader 86')
12h00 (10h00 GMT): Lesotho vs Zimbabwe - Nkana Stadium
15h00 (13h00 GMT): South Africa vs Mauritius - Nkana Stadium