Kolkata, Feb 17 (IANS) India tightened their grip over the second cricket Test against South Africa, picking up key wickets on a rain interrupted fourth day Wednesday, but the fickle weather can still deny the hosts a victory that would keep them as the World No.1 Test team.

At stumps, South Africa were 115 for three, trailing India by 232 runs, with Hashim Amla (49) and Ashwell Prince (0) at the crease. Amla soldiered on as South Africa lost key wickets.

Only 34.1 overs were bowled during the day because of several interruptions due to rain and bad light.

The forecast for Thursday is more rain.

'There could be partly cloudy sky, rain or thundeshowers in some areas for the next 24 hours,' an official of the Regional Meteorological Centre, Kolkata, told IANS.

India, however, would fancy their chances to level the series with skipper Graeme Smith (20), last innings' centurion Alviro Petersen (21) and the experienced Jacques Kallis (20) back in the pavilion.

India had scored 643 for six declared in reply to the tourists' first innings total of 296 in the crucial Test which would not only decide the series but also the top slot among Test nations.

Rains robbed 221 minutes of playing time on the penultimate day.

The start of the fourth day's play saw a 93-mintue delay due to a wet outfield following overnight showers before bad light and rains shortened the post-lunch session by 40 minutes. It was no different in the post-tea session that began 3.20 p.m after a delay of 35 minutes. Only one over was bowled before the umpires' light meters were out and they found the light insufficient to continue playing.

All the three dismissed batsmen failed to capitalise on good starts as Indian spinners Amit Mishra (2/15) and Harbhajan Singh (1/31) took the wickets extracting turn from the deteriorating pitch.

Resuming at the overnight score of 6/0, South Africa lost the prized wicket of Smith in the morning session as the visitors reached 39 for one at lunch.

Mishra got rid of Smith in the penultimate over before lunch with a top spinner that beat the batsman and hit his frontpad in front of the wicket.

After lunch, Harbhajan plotted Petersen's return to the pavilion with a drifter that went off bat and pad into the hands of short leg.

Kallis and Amla then added 57 runs in 66 minutes before Mishra struck again. The youngster bowled a beauty of a leg-break that took Kallis' inside edge as the batsman offered a defensive shot, and Mahendra Singh Dhoni did the rest behind the wicket.

In the morning, under very overcast conditions, the umpires Ian Gould and Steve Davies carried out two inspections and decided on a delayed start at 10.30 a.m.

The pre-lunch period also saw medium-pacer Zaheer Khan stick to a line on or outside the off stump and induced an edge from Petersen in his third over as the opener slashed at an away-going ball but V.V.S. Laxman failed to reach despite diving full stretch at second slip.

Zaheer sustained an injury after bowling five overs, and could send down only one over after lunch, besides spending a long time in the dressing room.