'Rock were unsettled straight away and found it difficult to hold off the pace and power of the Garryowen forwards attack whose pick-and-go tactics were working to good effect in the first half.
In such difficult, muddy conditions, it was always going to be tough to rack up a considerable score and Garryowen were certainly guilty of squandering numerous chances in the first half but it was clear that the scores were coming.
Leading 3-0 at half-time, Garryowen got their break 13 minutes into the second half when hooker Robert Meyer cleverly intercepted a pass as 'Rock were sloppy in clearing the danger in their 22 and he dived over under the posts for the only try of the afternoon.
Scrum half Conor Murray kicked three penalties and converted Meyer's try to help his side to the much-deserved victory.
Speaking to IrishRugby.ie after the match, Garryowen coach Paul Cunningham pointed out the significance of such a determined win.
"We take good confidence out of this. We've lost a couple of league games, so it was nice to get a win today and then we'll have a break next week," said Cunningham.
With the adverse weather conditions having some an effect, Cunningham granted that Saturday's match was unlike the earlier league meeting between the two teams, however he was quick to praise the diligent work of his players.
"It was a totally different game to the one earlier this year but that's the nature of the league and the cup this year and I think when the conditions are like that, any team has a chance.
"We played very well up front and 'Rock are good in that area. We did well at the breakdown in the second half, we kept control of the ball. So overall it was a good win."
Importantly for Garryowen, Cunningham remains optimistic about the Limerick men's chances in the league despite being bottom of the Division 1A table.
"There are only four games down in the league, another ten games to go.
"We had a couple of injuries at the start, we lost a couple of close games like the game against Cork Con but hopefully we can get them back again.
"We've two big games before Christmas, so if we could get results there it would put us right back in contention."
Although Blackrock were missing many of their stars due to Leinster's British & Irish Cup fixture against Plymouth, coach Barry Gibney was discontented with the overall performance.
"I don't think we played too well. We had a few guys missing and I don't think Garryowen were too effected by the interprovincial 'A' competition. But the guys have to step up and perform when given the chance," he said.
After losing their last two league games, Gibney admitted that his side have a tough task ahead of them when they come up against Division 1A leaders St. Mary's College on Decemeber 5 at Templeville Road.
"We'll be focusing on how we pick ourselves up after two league defeats and get back to winning ways and that will be tough.
"We have to go out to Mary's to do that and they're top of the league. So we have to bounce back well."