The win gave Indians an unassailable 3-1 lead in the five-game series with a match to spare. Chasing 213 for victory, the Indians were in trouble at 59 for four but Chawla and Tehlan put up an unbroken 95-run partnership for the fifth wicket to put the pressure back onthe Aussie bowlers.
When the heavens opened, the Indians were 154 for four in 33 overs, considerably ahead of the target of 127 at that stage, resulting in the match going in their favour accordingto the Duckworth-Lewis calculations.
The top order had again let India U-19 down with the team losing early wickets during the run chase.
The openers, S Anirudh (2) and Ankit Rawat (11) fell cheaply. However, Rohit Sharma played some handsome strokes in his 30 (off 43 balls with three fours), but when he departed caught at mid-on trying to clear the infield, the victory target seemed a long way away.
Chawla, however, showed his intentions hitting the first ball he faced past point for a boundary. In fact, that over from Patrick Darwen went for 12 and the Uttar Pradesh ladrepeated the dose to Jack Mc Namara.
When Chawla (49 off 52 balls with five fours and a six) was scoring freely, Tehlan (42 in 61 balls with three fours) was content to give him support. But in the course of time, healso picked up his scoring rate and did not allow the visitors any respite.
Their partnership, which came off only 100 balls, ensured that the asking rate was never a problem for the Indians and they had enough margin when the match was stopped due to rain.
Earlier, put in to bat, Australians were in trouble at 90 for five in the 19th over. But a 112-run stand off 164 balls between David Warner and Philip Wells saved them from a fate similar to that in yesterday's match where they were bowled out for 129 in little over 30 overs.
The Aussies could not put a partnership together in their top order and skipper for the day, Graeme Skennar (23 off 18 balls with two fours and a six) and Tom Cooper (37)were dismissed trying to force the pace.
But Warner and Wells were more circumspect and played according to the merits of the bowling. They rotated the strike efficiently and kept the scoreboard ticking.
Both of them got their 50s off successive deliveries. Warner's 56 off 104 balls had just one boundary while Wells' 50 off 80 deliveries had four hits to the fence.
The Indians employed surprising tactics of having no fielder inside the 30-yard circle on the leg side when the spinners were in operation.
The Australians were handily placed at 184 for five after 40 overs but just as the duo tried to push the scoring along, they got out and the batsmen to follow were frustrated by somedisciplined Indian death bowling.
In fact, the last 10 overs yielded just 28 runs and the visitors were bowled out off the last ball of the 50th over.
Left-arm spinner Ali Murtaza (3-37) and Abu Nachim (3-23) put the brakes on the scoring with the latter helping himself to a hat-trick when he got the last three wickets offthe final three balls of the innings.