Champions Valletta started their BOV Premier League campaign with an upset as a goal by Bojan Kaljevic mid-way through the first half gave Mosta a narrow win.
It was a disappointing performance by the Citizens who missed a penalty a few minutes before the Blues managed to take the lead.
Nicky Vella, Ryan Camilleri, Hugo Faria and Raphael Kooh Sohna were all making their first league appearance for Valletta but Roderick Briffa was unavailable as he is still recovering from an injury. Mosta, on the other hand, had Sasa Jovanovic, Nemanja Milovanovic and Kurt Magro making their debut while Adrian Borg was back after spending the last two years on loan with Hamrun Spartans. Jonas Rodrigues Ekani and new recruit Pedro dos Santos Calcado were ruled out through suspension.
Valletta could have taken the lead on the 18th minute when they were awarded a penalty after Adrian Borg handled the ball inside the area but Lateef Elford-Alliyu’s effort from the penalty spot was turned into a corner by Omar Borg.
On the 23rd minute, Mosta forged ahead as Bojan Kaljevic’s long-distance effort surprised goalkeeper Nicky Vella with the ball ending at the back of the net.
Kooh Sohna was unlucky to hit the foot of the post with a low shot from the right on the 34th with the ball ending in the hands of Omar Borg and just before half-time, a Ryan Fenech effort was saved in two attempts by the Mosta goalkeeper.
Seven minutes in the second half, Abdelkarim Nafti went close for Valletta with a direct freekick which scraped past the post. Christian Caruana tried his luck with a shot from outside the area when served by Bajada but Omar Borg blocked his attempt.
MOSTA Omar Borg, Tyrone Farrugia, Adrian Borg, Dyson Falzon, Ryan Grech (85′ Karl Pulo), Bojan Kaljevic (90+3′ Kyle Frendo), Sasa Jovanovic (73′ Kurt Zammit), Nemanja Milovanovic, Daniel Mariano Bueno, Kurt Magro, Manolito Micallef.
Subs not used: Kyle Gerada, Gianluca Vella, James Brincat, Aaron Sammut.
Coach: Enrico Piccioni
VALLETTA Nicky Vella, Jonathan Caruana, Ian Azzopardi, Steve Borg, Ryan Camilleri (32′ Luke Dimech), Ryan Fenech, Hugo Faria (77′ Luke Montebello), Raphael Kooh Sohna, Lateef Elford Alliyu, Shaun Bajada, Abdelkarim Nafti (61′ Christian Caruana).
Subs not used: Yenz Cini, Llywelyn Cremona, Ian Zammit, Adrian Zahra.
Coach: Gilbert Agius
Referee: Fyodor Zammit
Assistant Referees: Duncan Sultana, Jurgen Spiteri
Fourth Official: Philip Farrugia
Yellow Cards: Magro, Pulo
Scorers: 23′ Bojan Kaljevic
BOV Player of the Match: Omar Borg