After an up-and-down first round, Tiger Woods responded with a five-under-66 second round at the 2018 Dell Technologies Championship at TPC Boston on Saturday.

Woods ended his day at four-under for the tournament and six shots back of the lead.

He started the day at one-over after he had three birdies and four bogeys on Friday. That had him a ways down the leaderboard to start the day, as Tyrrell Hatton (eight-under 63 in Round 2) and Justin Rose (67) led the way at 10-under for the tournament. But as Hatton showed, a lot can change over the course of 18 holes.

Woods slowly started to chip away at the lead, nabbing his first birdie of the day on the third hole:

The next three holes saw Woods hold his ground with pars on each, but he once again made up some ground with a birdie on the seventh for the second straight day.

Woods made it through the front nine at two-under, which was one stroke better than his front-nine score in Round 1. But after Friday's struggles, all eyes were on the back nine.

In the first round, the 42-year-old American bogeyed three of the first seven holes on the back nine, including No. 10. The second round was a different story, though, as he carried the momentum from the front nine over.

A birdie on the 10th put him at three-under for the day:

But he wasn't done moving his way up the leaderboard. Birdies on the 14th and the 17th helped him climb all the way up to a tie for 21st, and at six strokes back of the lead, he remains in striking distance.

When it came to driving the ball, few have been better than the 14-time major champ:

As the Golf Channel's Brandel Chamblee noted, this was one of Woods' best performances in some time:

It wasn't a flawless day for Woods on the links, but he was able to limit the damage when he found himself in tough spots. Then again, he also had some missed opportunities that could have made this an even better round. He had a couple of birdie attempts lip out, including on the final hole of the day.

Overall, Woods has to be happy with his performance on the day. He managed to put his troubles on the back nine from Friday behind him and use that same stretch to surge on Day 2. A three-bogey back nine on Friday turned into a three-birdie momentum-booster in Round 2. And that proved to be the key to getting back in contention.

It's been 12 years since he won this event, but he's lurking as the tournament has reached the midway point. If he has any chance of capturing his first PGA Tour victory since August 2013, he's going to need more performances like Saturday where he played largely mistake-free golf for 18 holes.