In soggy conditions and rain falling for much of the match, Melbourne found that without a spine it's hard to get all the parts moving in the right direction.
The competition leaders were missing hooker Cameron Smith, halfback Cooper Cronk and fullback Billy Slater who were all absent on Queensland State of Origin duty.
The Storm completed 18 of 19 sets and only missed seven tackles in the opening half but without that star trio their attack looked rudderless and they struggled to convert their pressure into points.
The teams traded penalties for the 2-2 halftime scoreline, with Benji Marshall kicking his in the seventh minute and Widdop equalling after the halftime hooter.
The visitors should have scored twice - through Marshall and Lote Tuqiri - but for some desperate one-on-one defence from Storm wingers Anthony Quinn and Justin O'Neill.
But Tuqiri made no mistake when he got another opportunity in the 43rd minute.
Skipper Marshall orchestrated an overlap and sent the ball wide to Tuqiri who despite a ball-and-all tackle by fullback Matt Duffie got the ball down.
After O'Neill dropped a Marshall kick cold, the Tigers ran a set play off the scrum and Beau Ryan found winger Matt Utai on the charge and all of a sudden his team were eight points clear.
To Melbourne's credit they refused to lay down and threw everything at the tiring visitors as the clock wound down but couldn't find the elusive try they needed.
The only downside of the night for the Tigers was a hip injury in the warm-up ruling out fullback Tim Moltzen while Liam Fulton looked ginger as he left the field, reportedly with back spasms.
Tigers coach Tim Sheens said the pair could be right for their next clash with the Sydney Roosters.
Sheens said the arm wrestle was as he expected.
"It was hard to come up with points ... the two early (second-half) tries surprised me," he said.
"At the end of the day we just defended it but it was a tough night and the conditions were heavy going so I was really pleased with the squad."
Marshall said his team wasn't getting carried away with the win given the absence of Melbourne's big three.
"We're just happy to get the two points," Marshall said.
"If we play them again it's going to be a different story with those players there."
Bellamy said the effort of his players was "tremendous" - particularly in defence - but they let themselves down with poor execution at times.
"We couldn't quite find our rhythm with attack," Bellamy said.
"We made some ground and some linebreaks but we couldn't quite finish it off.
"We didn't have the polish, especially with our kicking close to the line."
- AAP
