Aiden O’Brien insists Millwall have not achieved anything yet as they bid to secure promotion from League One through the play-offs.

Neil Harris’ side guaranteed a top-six finish on Saturday with an impressive 3-0 win over Oldham.

After an indifferent start to the season, the Lions have rallied well and could still clinch third-place with a win at Gillingham on Sunday.

O’Brien said: “We are in the play-offs but we haven’t done nothing yet.

“You can lose in the semi-finals and you’re back to square one again – you’ve got to start again and prepare for the same league all over again.

MORE: Millwall boss hails defender after Oldham brace

“We’re in a privileged position but we need to prepare well and keep doing what we’re doing and hopefully everything goes right for us.

“The boys are buzzing. We are all ready to go. Hopefully we can get another result at Gillingham and then can prepare for the first play-off game.”

Byron Webster gave Millwall an early lead at the Den with a fine header, before Shane Ferguson doubled the advantage.

Webster then doubled his tally for the afternoon with another header as Oldham failed to deal with the Lions’ aerial presence.

Walsall, Bradford and Barnsley are currently joining Millwall in the shot for promotion, although Scunthorpe and Gillingham also have an outside chance of breaking into the top six.

O’Brien insists he has no preference to who Millwall face in the semi-finals.

The 22-year-old said: “I don’t mind personally who we play. But I can’t talk for others – I don’t know what the gaffer sees or anyone else thinks.

“But I feel we’re better than [most of the teams] in this league if not all of them.

“I’m ready for whoever comes.”

Follow us on Twitter @NewsShopperSprt