Gallacher, a four-time European Tour winner, made the cut for just the second time in eight starts after carding a five-under 67 at the Surrey venue to sit alongside Drysdale on four-under after he shot a second successive 70.
David Law (69) and Richie Ramsay (70) also progressed on three-under, as did Grant Forrest (72) on two-under, but it was Gallacher who seemed the happiest among the quintet after he enjoyed a welcome return to form.
The 46-year-old, who is close to clocking up his 600th appearance on the circuit, is exempt for another season on the back of his 2019 Hero Indian Open win but, nonetheless, he’s not happy to be sitting 148th in this year’s Race to Dubai.
“I’ve struggled all the way through Covid, to be honest,” said Gallacher. “Everything has been a nightmare from travelling to sitting in our rooms 24/7 almost after I’ve had 20 years of playing golf, going out for dinner and not talking about golf.
“Now everything is going back to a bit of normality in that respect and also with crowds, and that’s what I am used to playing in.”
Gallacher, who first teed up in this event in 2000, finishing fourth in 2010 then tying for fifth four years later, started his second circuit with a bogey before mixing seven birdies with one bogey thereafter.
“I played lovely today,” he declared. “I never missed a shot on the front nine and was out in three-under having missed two putts inside probably six feet.”
Describing the condition of the Wentworth course as “phenomenal”, the 2014 Ryder Cup player is hoping to kick on over the weekend at the venue where his uncle Bernard has a statue on the first tee to mark his time as the club’s professional.
“If I play like that anyway,” he replied to being asked if he could get himself in the mix over the final 36 holes. “I have worked hard this week with wee Alan (McCloskey). I’ve spent a lot of time on the range and, though it’s been knackering, I hit it really good today. There’s a lot of promising signs.
“This is my 25th season and I’ve got my 600th event in a month’s time. I think you do doubt yourself every now and again through just getting old. I’m 47 in November.
“But it’s days like this that show you are still hitting it long enough and you definitely take heart from shooting five-under on a tough track.”
Drysdale, who sits six spots outside the all-important top 125 as he bids to retain his card for the 18th consecutive season, has also been pleased with his work so far in the $8 million event.
“I want to be here for the weekend at every event, but you absolutely want to be around for the weekend here,” said Gallacher’s fellow 46-year-old, who was chuffed with his birdie-birdie finish.
“The last few cuts I made on the UK Swing I had two good rounds out of four so hopefully I can have four here.”