Every point was precious in a match turned into a classic forwards' battle by the weather, and it was the Troon side who ultimately found themselves on the right side of the final scoreline despite Irvine having more than enough chances to put them away.
Victory would have put Irvine level on points with Marr in second place, but as things stand third may now be the best they can manage.
The first half was largely played in midfield with the home side, playing with the wind, making use of tactical kicking to pin the visitors back in their own half, and the visitors keeping the ball in the forwards and patiently working upfield through a combination of rolling mauls and pick-and-drives.
It took until six minutes before half time for the deadlock to be broken. Irvine had been in possession deep in the Marr half for several minutes by the time Danyl Davies pounced on captain Kevin Lang's kick through to the right corner to score his 21st try of the season. Unfortunately it was also scored in the "wrong" corner in terms of the difficulty of the conversion and Kris Hobson was unable to score.
Irvine could have extended their lead in injury time when they again forced a number of good positions in the Marr 22 but they were ultimately ruled to have been held up over the line, and the home side turned around with a slender 5-0 lead.
In the second half the roles were reversed with the home side now playing into the wind and having to adapt their tactics appropriately.
The visitors used the relatively greater freedom playing with the wind now gave them to dominate the opening exchanges, and after the home side had repelled a number of good spells of pressure on their try line, Marr won a penalty in a kickable position on the left touchline which visiting fly-half Ruaridh McGee scored to reduce the deficit to 5-3 after 55 minutes.
Irvine were well aware of the precarious position they now found themselves in and set about trying to regain the initiative.
They thought they had done so shortly after the hour on another kick play but on this occasion the visitors were able to get bodies back. Another attack was intercepted and cleared to touch, before the home side produced another long spell of try line pressure which ultimately came to nothing.
The possession from which the visitors won the game was set up shortly afterwards, when the home side committed a knock-on in front of their own posts. From the resulting scrum, the visitors laid siege to the Irvine line and were held up twice as the hosts battled to hold on to their lead.
But their hard work was undone on 80 minutes when they conceded another kickable penalty on the left flank, and McGee nervelessly stepped up to score the goal to put the visitors in the lead for the first time.
Irvine had plenty of possession during five frantic minutes of injury time but they were unable to get into a scoring position and Marr saw the game out to claim the points.
Next up for Irvine is a trip to the Bearyards to play Allan Glen's, while Marress have a friendly at Lenzie.
IRVINE -- D Davies; C Lang, K Lang (capt), A Spiers, S Nunan; K Hobson,
C Hobson; D Kirkwood, S Docherty, J O'Neill, T Wright, G Kerr, A Lang,
A Maxwell, R Filander. Replacements: R Festorazzi, M McGonigal, R Campbell.
MARR -- C Bickerstaff; S Bickerstaff, S Reddox, D Steele, A Galt;
R McGee, A Bate; R Kennedy, S Adair (capt), F Ferguson, F Young,
K Kirk, S Kirk, P Burke, F Grant. Replacements: R McNicol, K Vallance,
REFEREE -- Mick Longton
MAN OF THE MATCH -- Ruchin Filander (Irvine)
MASCOT -- Taylor Sweeney