Back-to-back defeats against Leicester and Toulon had put Ulster's challenge on the rocks until a 24-9 bonus-point victory over GUINNESS PRO12 rivals Scarlets at the Kingspan Stadium on Saturday kept Neil Doak's side in contention.
Pienaar made a telling impact on his first appearance for the Ulstermen this season after suffering a knee injury with South Africa in September, scoring a try and setting up Tommy Bowe to touch down.
And despite being sin binned in the 76th minute, the 30-year-old received a standing ovation and admits he is relishing the chance to inspire his side to greater success this campaign.
"It was really nice to get back playing again after three months," Pienaar told The Irish Times. "It was nice to get 76 minutes before the yellow card and it was nice to get a run out.
"Obviously there is a lot to work on fitness-wise and also I was a bit rusty in some areas but, all in all, I was pleased to play.
"I'm always hard on myself and I know I made a lot of mistakes. Service-wise, I probably gave a couple of bad passes and made a couple of wrong decisions. Hopefully I will be sharper over the next couple of weeks.
"It was disappointing with those first two results in the European Cup. I think we have given ourselves a good chance to still be in this pool. It's in our hands now. We have three games left and hopefully we can get three big results.
"As a team we haven't played as well as we have wanted but we have managed to grind out wins. We are still working hard on the small details. I think we have a great group of guys and we are heading in the right direction."
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