Mashego on Saturday reasserted his value by scoring a late winner against Kaizer Chiefs in the inaugural Premier's Cup at Sisa Dukashe stadium.
The 35-year-old 'Mahoota' is one of a few footballers to have won every PSL trophy on offer. Despite his achievements, Manzini says the Bushbuckridge-born player remains down to earth.
"A very good professional and a very good player," Manzini tells KickOff.com.
"I think he is still the best and having someone like him [being at Chippa] it's a blessing, he is very important... his experience is so amazing and he is very professional."
United begin their 2017/18 season with a visit to Orlando Stadium to face a wounded Orlando Pirates next week Saturday, with Manzini expecting a contest in Soweto.
"Yeah it's not going to be an easy game against Pirates but so far our preparations for the new season has been great and the team is settling well.
"The club has assembled a very good team and the [new] guys are settling in well."
Meanwhile, Manzini downplayed his absence from the squad that beat Amakhosi amid rumours linking the former Bloemfontein Celtic man with Steve Komphela's side.
"Only 11 players can start and we have a big squad this season... it's still about preparations and the coach is looking at different combinations. But so far so good."