Emus captain Nigel Staniforth described his side as "dumb" in the first half, as ill-discipline and a string of penalties resulted in winger Tom Green being sin-binned and the Roos going into half-time with a 22-19 lead.

But the experienced Emus were much more poised in the second half and two tries to Harris inside the last 10 minutes secured a 36-29 victory, a fourth in seven rounds for the defending premiers.

"They (Roos) stuck at it and have got a good system they've clearly worked on and we were a bit dumb. Too many penalties," Staniforth said of the first half.

"We've just got to leave the ball and readjust but four times from kick-offs after scoring a try we'd make a big error and let them straight back in.

"We talked at half-time and luckily adjusted and if we didn't we wouldn't have won."

For the Roos it was yet another close-fought defeat.

As has been the case numerous times in the first six rounds of the season, lapses in concentration and some unfavourable decisions resulted in the Roos being beaten in the final few minutes.

"We can't manage to close games down and in a competition like this with teams like this we're not mentally there yet," Roos coach Simon Petelo said.

"At the moment we're really struggling."

While the Roos are failing at finishing games, for the bulk of Saturday's match they were up for the contest.

Emus started the better at No. 1 Oval and after banging through the middle with their renowned forward pack, they opened the scoring via a Charlie Henley try.

The sides then swapped tries, Tim Beach crossing yet again for the Roos before Tom Green snagged a simple intercept, before the hosts started to take control as Emus' discipline failed them.

The visitors gave away a string of penalties and the Roos, off the back of a strong rolling maul, scored twice through hard-working hooker Chris O'Shea to lead 22-19 at the break.

Emus also had Green sin-binned shortly before half-time but the visitors still scored first in the second stanza, a penalty from captain Staniforth locking things up.

The game became an enthralling arm wrestle and both sides had their chances in the final quarter, with Roos winger Beach having a second try disallowed after a forward pass ruling.

With nine minutes remaining another forward pass call went against the Roos, this time during an Emus attacking raid, and the greens played the whistle. After some quick hands Harris came bursting onto the ball and through a hole before racing away to score an all-important try.

Harris grabbed a second in similar fashion soon after to confirm the bonus point and a fourth win from seven games.

"We weren't that clinical with a few things today but when you come over here and get the bonus point win you take it," Staniforth added.

Henley, heading into the weekend as one of the top point-getters in in the Central West Player of the Year race, was again among his side's best alongside fellow Emus Rob Thorburn and Scott McLean.

The loss for the Roos was compounded by a lower leg injury to hooker Ned Williams while captain Shaun McHugh suffered a similar injury but was able to finish the game.