That's all from me folks. Thanks for your company on a great night for Aberdeen, a twitchy one for West Ham and a frustrating one for Inverness. We'll do it all again next week...
- FT: West Ham 1-0 Birkirkara FC
- Late, late Tomkins goal for Hammers
- FT: Inverness CT 0-1 Astra Giurgiu
- Budescu free-kick gives Astra win
Inverness midfielder Ryan Christie
"I think we expected them to be better than they were, which is a positive for next week. Every player in the dressing room knows this tie is not over."
We'll bring you reaction from Dons manager Derek McInnes on the BBC Sport website later, so pop back and see what he had to say. He's sure to be thrilled after such a fantastic result.
Caley Thistle manager John Hughes
"We certainly deserved something from the match and we're disappointed to lose a goal from a cheap free-kick. We dominated the ball but we needed to do things quicker. One or two of my boys are looking for a bit more fitness but I'm proud of them all.
"I thought our shape was good, we coped with their counter-attacking well.
"We're still well in the tie. I don't know if they will open up at home or be a bit nervous in front of their own fans."
Dean Glass on Twitter: "#bbcscotfootball This was Rijekas first home loss in 13 and second home loss in 53. And that's unbeaten run included PSV and Sevilla"
Dougie Kinnear on Twitter: "Great team performance from The Dons tonight! Front to back we have been strong! Massive improvement v last Thursday! #bbcscotfootball #COYR"
Andrew Duffin on Twitter: "Aberdeen doing their best to stop all the arguments about Summer football. #afc #bbcscotfootball"
The return of Richie Foran from long-term injury is probably the only bright spot for Inverness. Will the Irishman be able to play from the start in Romania next week? It might be too much to ask of player who has been out since March 2014.
What a night for the Dons! That is a simply stunning result. The visitors survived a few early scares but held on and made the Croats pay with some deadly finishing. Andrew Considine, Peter Pawlett and Kenny McLean were the scorers.
It could have been 4-0 in the closing minutes as Adam Rooney thumped a good chance over the top after good work from Shay Logan and McLean.
Former Inverness forward Barry Wilson on BBC Radio Scotland
"Inverness passed the ball really well but they didn't have anything up top. They had two or three half chances and a draw might have been fair. In Budescu, Astra had the best player on show."
Four minutes of stoppage time are signalled as Danny Ward makes another good save, this time batting away a firm 20-yard strike from Anas Sharbini.
Former West Ham midfielder John Moncur on BBC Radio London: "The positives are that it was a good workout very early in the season and apart from Kevin Nolan there were no injuries.
"They have won a game which looked like being 0-0 by nicking a goal at the end. It will be a different game away from home. Birkirkara played tonight like it was a cup final for them. Can they work that hard again? We'll see.
"If West Ham had won 5-0 tonight Slaven Bilic could have left his key men at home next week but now they will all have to come to Malta."
Rijeka have not given up and are determined to give themselves some hope for the second leg at Pittodrie next week as Marin Leovac lifts a shot over the crossbar.
Adam Rooney comes on for the final 15 minutes, replacing David Goodwillie up front.
The first European tie played in the Highlands ends in disappointment for the home team. Inverness certainly gave it a good go against experienced opponents but they were lacking a threat in the final third.
The tie is by no means over and Caley Thistle have made a habit of upsetting the odds.
Into stoppage-time now and Inverness are huffing and puffing in search of a last-gasp equaliser.
Danny Ward makes a fantastic block to keep out a shot from the sliding Roman Bezjak. A point-blank save inside the six-yard box.
Former West Ham midfielder John Moncur on BBC Radio London: "That goal releases the pressure. In the second leg they are going to have to come out and score which will play into West Ham's hands. Sometimes away legs can be easier for the bigger team. There will be space for West Ham to attack in the second leg."
Golfer Paul Lawrie on Twitter: "Awesome stuff."
He's talking about his beloved Aberdeen, although it could equally apply to his round of 66 at St Andrews today.
Huge relief at Upton Park as the Hammers finally go ahead against the third-best team in Malta.
West Ham get the breakthrough! Goalkeeper Justin Haber has looked suspect all night and he misses a corner, allowing centre-half James Tomkins to chest it home on the line.
The crowd at Upton Park is confirmed as 33,048. Astounding effort, for a very forgettable game.
Aberdeen are in dream land... Shay Logan gets his head to a poor clearance, David Goodwillie then dinks it into the path of Kenny McLean and the substitute cracks a volley beyond the exposed keeper for his first goal for the club.
Here comes Richie Foran and the skipper gets a raucous welcome from the Inverness fans as he replaces Dani Lopez.
Former West Ham midfielder John Moncur on BBC Radio London: "Hard work and organisation go a long way. Birkirkara have really impressed me in the second half."
It's a double change for the hosts as Jordan Roberts comes on for his Caley Thistle debut, along with David Raven. Ross Draper and Josh Meekings are the men making way.
After those changes, Dani Lopez runs on to a smart Aaron Doran pass but can only shoot straight at the keeper.
Mark Noble heads across goal - nobody there. What a frustrating evening for the Hammers...
SIX MINUTES left. Who saw this scoreline coming?
The Dons make another change as Kenny McLean takes the place of Niall McGinn. The Northern Ireland international grabs two bottles of water as he makes his way to the bench drenched in sweat.
Aaron Doran shifts the ball on to his right foot and takes aim for the far corner from just inside the penalty area but the ball whizzes narrowly wide.
West Ham's frustrating night continues. Skipper Kevin Nolan heads straight for the tunnel after suffering a shoulder injury and is replaced by Diego Poyet. Time running out for the Hammers.
Aberdeen make a change as Willo Flood replaces goal-hero Peter Pawlett in midfield.
Rijeka are dominating possession but at the moment are not anywhere near as dangerous as they were in the first half.
Nicholsons & Scott's: "Keeping up in the Algarve via BBC. COYR"
The home side need a spark from somewhere as Astra take the pace right out of the game and silence the frustrated crowd. Richie Foran is on the bench after missing all of last season through injury. Could the Inverness skipper come on for an inspirational cameo?
It's been a bad night for West Ham so far and it could be about to get worse. Kevin Nolan has needed treatment on a shoulder injury and now Joey O'Brien is holding the back of his hamstring.
Inverness are lucky as the visitors miss a sitter in front of goal. Constantin Budescu threads a wonderful pass through to Brazilian William, who can only graze the outside of the post when he should be finding the net.
Former West Ham midfielder John Moncur on BBC Radio London: "The team Slaven Bilic put out was to put a statement out and go and win the game comfortably. It hasn't worked out like that."
Aberdeen midfielder Jonny Hayes tries to find the near post with a free-kick from the right but puts to much bend on his effort and the ball spins wide.
Elliot Lee - who scored the winner in the last round and is the son of former England midfielder Rob Lee - replaces Modibo Maiga up front for West Ham. And his side need a real injection of urgency here.
This is shaping up to be a remarkable result for Aberdeen. Remember, Rijeka are unbeaten at home in their last 12 European ties and are aiming to reach the group stage for the third year running.
Is the honeymoon over for Slaven Bilic already? Boos ring out at Upton Park as a Hammers back pass triggers more frustration from the home support. It's not going to plan. Defender Joey O'Brien has just been booked for a challenge on Ryan Camenzuli.
Final change for the Maltese side as Vito Plut replaces Liliu. The visitors have gone three at the back as they look to close this result out. Just over 20 minutes remain.