As Ireland arrive at the final stretch of a gruelling and tumultuous World Cup qualifying campaign, Jeff Hendrick is in upbeat and philosophical mood, describing the past year as "a real learning process."

In the eyes of many, Ireland's qualification chances were already in ashes after their second game, a traumatic 1-0 loss at home to Luxembourg in March.

Since that nadir, there has been a broad uptick in the quality of performances, albeit the 1-1 draw at home to Azerbaijan was another rough setback.

As far as Hendrick is concerned, Ireland have come through an awkward transitional period and the midfielder is positive for the next series of competitive games in the summer.

"When I saw the group, I knew it was going to be tough," Hendrick told reporters. "Portugal and Serbia are great teams. Only one qualifies by going straight through so we always knew it was going to be hard.

"We got new managerial staff and coaches. They were bringing through the younger players, which had to be done really to freshen up the squad.

"It's been a real learning process for the whole group, getting to know each other, improving and changing our style of play. Hopefully we can take that on to the next campaign."

Hendrick in action against Qatar

Hendrick received widespread acclaim after his masterful performance in midfield in the 4-0 demolition of Qatar last month. Many heralded it as a return to Euro 2016 form for the Dubliner, after a couple of tough seasons.

"Sometimes you can't put your finger on it. Why you gained confidence or lost confidence. For me always, I’m always working hard, striving to get better. Sometimes you just need something to click. You don’t exactly know what it is but you just roll with it. That seems to be the case.

"I’m working hard as ever, I’m just happy that my performances have improved and hopefully I will continue doing that."

Hendrick has occupied the bench for a fair portion of the campaign, only coming on as a second half sub in the opener in Belgrade and then sitting out the home matches against Azerbaijan and Luxembourg altogether.

The player didn't take the omissions as a slight - and even suggested it was something he needed.

"(Was I) concerned? No. There's very good players in the squad, everyone is due a chance to play in certain games. It wasn’t my moment to start a game but I had time to reflect and look at my own game.

"I think it’s worked for me now. You’ve seen that in last few games; I think I’ve played well. Maybe that was something I needed.

"You never know in the moment but I’m enjoying what I’m doing right now and have got to build on that."

Hendrick controlling the ball under the nose of Diogo Jota

As for Thursday's game, Hendrick says Ireland are driven by the hurt of the late sucker punch in Faro, when a terrific Irish performance, which so nearly yielded a landmark victory, was soured by two late Ronaldo headers.

"We were hurt after the last game, the effort we put in. When you play a team like that, you know it's going to be hard. We had a gameplan and it worked really, really well, up to the 88th minute.

"We'd kept Cristiano Ronaldo quiet for the whole game - that's why he's a top player. To have such a quiet game and score two goals is brilliant for him, but that hurt us.

"We have to try and put out that same level of commitment and hard work. We didn't do too much wrong out there, but we've worked hard on what we can improve from that performance."

Follow the Republic of Ireland v Portugal via our liveblog on RTÉ.ie/sport and the RTÉ News app, watch live on RTÉ 2 and the RTÉ Player, or listen to live radio commentary on 2fm's Game On.