Sergio Garcia dug deep to stay in contention at the Andalucia Valderrama Masters as Joost Luiten, aided by a spectacular albatross, claimed the halfway lead.
Luiten revived his challenge in some style when he holed out from 227 yards for a rare two at the long 11th, although he did bogey two of the last four holes to see his advantage trimmed to one shot on six under par.
Tournament host Garcia did well to salvage a 71 with a birdie at 17 and a good up and down at the last which kept him in a share of second with Robert Rock and Scott Jamieson, but Jon Rahm's first competitive appearance in his homeland ended in disappointment as he missed the cut.
The iconic Valderrama layout continued to enhance its reputation as one of the toughest tracks on the European Tour as only 15 of the 126 starters completed 36 holes under par, with Luiten claiming the outright lead after his remarkable back nine.
Luiten was one over for the day after a second bogey at the 10th, but he suddenly vaulted back to the top of the leaderboard with one perfect swing of a four-iron at the 11th, and he came agonisingly close to a slam-dunk hole-in-one at the next as the resulting birdie got him to eight under.
But the Dutchman, runner-up to Andrew Johnston at Valderrama in last season's Spanish Open, gave a shot back when he missed the green at the short 15th, and a plugged lie in a bunker at the 17th led to another bogey - his second six of the day.
Luiten safely parred the last to complete an entertaining 71, and he said: "I'm happy with the way I played. I finished second here, so I like this place. Hopefully we can have a good weekend and we can win here but there's a lot of golf to be played and we just need to focus and have another good round.
"I think it will play a bit shorter off the tee, it will be a bit harder maybe to hit the fairways if they're going to run off but it's still fairly soft, you can still be aggressive into the pins but you've got to hit the fairways and that's the game plan for the weekend. I think 10 under will be a good number."
Rock continued his encouraging recent form as he returned a workmanlike 70, although he took a little gloss off his round when he followed two birdies in three holes with a closing bogey at the ninth.
The English journeyman was later joined on five under by Garcia, who mixed three birdies with as many bogeys and admitted afterwards that he had aggravated his wrist injury over the last third of his round.
Scott Jamieson is also in the share of second after he recovered from a bogey at the second with three birdies in four holes from the fifth, and he picked up further shots at 12 and 16 before doing well to escape with a bogey-six at the 17th after blocking his drive out of bounds.
Jamieson's 68 made him one of only two players in the field to break 70 for both rounds along with Ben Evans, who boosted his chances of retaining his European Tour card with a second consecutive 69 featuring four birdies and two bogeys.
Former Ryder Cup player Oliver Wilson, who is languishing at 287th on the Race to Dubai, is also enjoying a strong week and birdied four of the last eight holes to card a 70 and close on three under with Ricardo Gouveia, who also return a 70 after he birdied the final three holes.
Johnston was just two strokes off the lead until he paid the price for a wayward drive at the last, running up a double-bogey six to slip to two under par as he signed for a 71.
But Rahm will not be around for the weekend after failing to recover from an erratic mid-round run of four bogeys in six holes, and the world No 5 managed only one birdie in a 75 which saw him finish on seven over - three shots outside the halfway cut.