Zeenews Sports Bureau
London: South Africa have set an imposing target of 346 runs for England to win the Lord's Test and level the series.
Finn, who has figures of 4 for 60, took three wickets from 29 balls on Sunday to revive England's hopes, after Hashim Amla's elegant 121 threatened to bat the hosts out of contention.
Amla scored his 16th test century from 205 balls with 10 fours before he was bowled by Finn, who then removed AB de Villiers for 43 and Jacques Rudolph for 11.
The only wicket to fall in a one-sided morning session was that of the nightwatchman Dale Steyn, who was removed by Stuart Broad.
After resuming on 145 for 3, Steyn was hit on the left hand as he tried to fend off a bouncer from Finn in the first over of the morning, but he batted for 42 minutes to frustrate England.
Steyn was eventually out to Broad for 9, caught at short leg by James Taylor, after a partnership of 33 with Amla, but the hosts then missed a huge chance in the 62nd over.
Having hit his first two deliveries for four, de Villiers was on 8 when he was bamboozled by Graeme Swann, chipping him to midwicket.
Anderson, falling forward, somehow failed to hold the catch and the feeling that England had just "dropped the mace" — the trophy held by the world's top-ranked Test side — set in.
Wicketkeeper Matt Prior had already dropped Amla, then on 2, on Saturday night and together with de Villiers had put on an unbroken stand of 52 by lunch.
Amla cut Jonathan Trott for four to bring up his century in the 78th over but with the game drifting away from England, Finn produced an unplayable delivery that crashed into Amla's off stump in the 89th.
England used its final referral after umpire Kumar Dharmasena ruled de Villiers was not out lbw to Anderson in the next over, replays showing that ball would have clipped the bails by less than the margin needed to overturn the call.
In the next over, however, de Villiers edged Finn to Strauss for 43. It was Strauss's 121st catch in Test cricket, an England record, but the captain then missed a difficult one-handed chance to snare JP Duminy off Swann.
It was England's ninth dropped catch of the series but the hosts shrugged off the blow, with Finn getting Jacques Rudolph caught behind in the 97th.
Duminy, who is unbeaten on 18, took a single in the session's final over to take the lead to 300. England has only successfully chased a target of 300 or more three times in Test history.
The Proteas, who lead the series 1-0, will replace England as the top-ranked Test team if they avoid defeat.