'The toughest session I've ever faced'

India opener KL Rahul says he's never faced fast bowling as challenging as what Pat Cummins and Josh Hazlewood produced early on day two of the fourth Test in Dharamsala.

Rahul successfully negotiated a hostile first-session burst from Hazlewood and Cummins on Sunday morning of the Test series decider.

Day Two report: Lyon preys on India

The tourists picked up just one wicket for the session, that of Murali Vijay for 11, but Rahul and Cheteshwar Pujara did well to limit the damage given the potency of Australia's fast men.

Cummins and Hazlewood generated a dangerous mix of pace, bounce, swing and accuracy with the new ball and Rahul, who eventually fell to a Cummins bouncer after lunch, has never seen anything like it.

"I can say it has been the toughest session I have faced in Test cricket so far," the 24-year-old said, having debuted at the Boxing Day Test in 2014 when he faced an attack spearheaded by Mitchell Johnson and Ryan Harris.

"They put the ball in the right areas, they swung the ball, they bowled with a lot of pace and a lot of venom.

Quick Single: India concede they're missing Kohli

"I was thoroughly enjoying it."

With the second new ball just four overs old, skipper Steve Smith will call on his new-ball pairing to step up again on Monday morning. India will resume at 6-248, with Australia holding a 52-run lead and the game in the balance.

Rahul noted the pitch was "obviously helping them as well", adding he was impressed with how Hazlewood and Cummins kept their pace up throughout their morning spells.

"The conditions were nice and cool so I guess they could bowl longer spells," he said.

"They didn't get really tired. You can say that he (Cummins) has been the guy who as a fast bowler has challenged us in this series."

Quick Single: Clarke, Haddin query India's tactics

Cummins, who suffered a series of serious injuries after sparkling on debut in 2011, played just his second Test last week in Ranchi.

He was sent for precautionary scans between Test and then given the green light to back up, and he hasn't shown any signs of fatigue despite the quick turnaround.

"He really showed he is world class," offspinner Nathan Lyon said of Cummins. "Josh Hazlewood has been the same.

Quick Single: Lyon reaps rewards of Plan A return

"The way Josh and Patty went about it was exceptional.

"They work well together and it's great signs for Australian cricket. It's exciting to see Patty Cummins back and bowling fast."