Showing how much the England paceman was in charge that series, Anderson only took on average 12.5 balls to dismiss Kohli, getting him edging each time - once caught behind, once at second slip and twice by Alastair Cook at first slip.
He claimed his fourth scalp later in the afternoon session as India, like England, were bowled out fairly cheaply after an assured start.
Root looked imperious, though, and punished any bad balls with four boundaries coming off his bat before lunch in a 57-run partnership with Jennings.
There were strokes played, few iffy strokes too made an appearance, but on a pitch which seems to have dried out, this could well be India's best chance to put up a massive first innings total.
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Winning the toss, England made a decision to bat first and despite stitching together a couple of 50-run partnerships and a single 100-run partnership, the Indian bowlers kept chipping in with wickets.
A match, and series, on a knife-edge.
With India suffering a collapse to rival England's from the previous day - losing five wickets for 50 runs - Kohli once again showed his skill with a fantastic century.
However, Root, along with wicketkeeper-batsman Jonny Bairstow, steered the home side away from danger as they partnered a 100-run stand between them to shift the momentum and the control of the match back England's way. "I was working on simplifying my actions a bit and make sure I can get more body into the ball, try create something in the air and it worked really well", he said.
"It just happens to be the ball before I got out and suddenly there's a huge sort of hoo-ha about a pigeon".
Curran hit the ideal length as first-change bowler and immediately trapped Vijay lbw in the 14th over.