Philippe Clement’s side made history by becoming the first Gers team to beat a Spanish side on home soil at the 14th attempt.
It also means the club topped their Europa League group and reached the last 16.
Super sub Kemar Roofe notched a late winner after Abdallah Sima and Cyriel Dessers strikes were cancelled out by the La Liga side.
Midfield powerhouse Lundstram reckons everyone played their part and was full of praise for the entire squad.
Speaking to RangersTV, he said: “I thought we were brilliant. I said to the lads at half-time we had been really good.
“Kem came on and put a shift in, I thought Cyriel was magnificent all night, he put himself about and worked his socks off.
“Sam Lammers was brilliant, it was a top performance for everyone and you don’t get results like that unless everyone plays well against some top talented players.
“They hurt us a few times with some slight mistakes where you maybe don’t get punished against lesser teams.
“We held our own against a top team we created a lot of chances, the lads at the top held it up well and it was a really good away performance.
“It is a really pleasing, and famous night for the club.”Gaffer Clement has worked his players hard since arriving at the club in October and is now 13-games unbeaten.
Lundstram says the win over Betis shows putting in the hard graft is paying off and now he says the players hope to continue the momentum in Sunday’s Viaplay Cup final against Aberdeen. He added: “We have been putting the hard yards in at training.
“We have had game after game after game and the lads are giving it everything. It is paying off and we want to keep that going.
“It is game by game at this stage, they are coming thick and fast but we want to build up some momentum.
“We want to keep our league form right up there and we have Europe as well.
“We can look to the final now. We were looking forward to it in the background as we had other games but now we want to put in a performance that gets us over the line.”