At Mutesa II Stadium, Ronald Magwali's 30th-minute header from a Fred Agandu cross proves decisive.
The 10-time Cup winners bowed out of the competition 3-4 via a decisive penalty shootout against Maroons at Kavumba Recreation Centre.
Express hold a rich history in the competition, having won it 10 times - and are joint record-holders with KCCA.
Proline gaffer Abubaker Mbowa said victory will boost the confidence of his side as they battle against the drop in the league.
After eliminating Vipers from the Uganda Cup, surprise package Kajjansi United are keen on ruffling more feathers - this time of SC Villa in the round...
Vipers SC sack head coach Edward Golola and his entire technical team, a day after being knocked out of the Uganda Cup.
He will be assisted by Mark Ssonko and Issa Masembe
Goalkeeper Hamuzah Muwonge saved three penalties
Proline should have won the match in normal time but they were guilty of squandering plenty of goal scoring opportunities
Express are joined in semi-finals by Bright Stars and Kyetume
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