I was delighted to get three wickets but I was chasing others too much, admits Finn

Competition for places can generate improvement in sport, but it can also push players to try too hard. So it was for Steven Finn, who took three important South African wickets here yesterday but admitted he had sometimes allowed his heart to rule his head.

Preferred to Tim Bresnan as England's third seamer for this Test, Finn knows he has a fabulous opportunity to cement his spot in the side. This is the first time he has played back-to-back Tests since December 2010.

Finn tore through the South Africa top order with a spell of three wickets in seven deliveries, although two of his victims, Alviro Petersen and Jacques Kallis – controversially – fell to leg-side strangles. Indeed, the day was Finn's Test career in microcosm: wickets, but at a higher price than he would like. The Middlesex paceman ended up with figures of 3 for 68 from his 16.4 overs.

"I was delighted to get three vital wickets, which enabled us to assert ourselves," said Finn. "While I was happy with that, maybe I chased wickets a bit. I was told I was in the team on Wednesday afternoon and I was trying to come in not so much as an enforcer, but a wicket-taker, and maybe I searched for it a bit. Hopefully on the second day I will bowl well again.

"The guys who missed out are high-class bowlers. Tim Bresnan has performed well in the England team for some time and Graham Onions took nine wickets for Durham yesterday."

Both England and South Africa banned questions about the removal of Kevin Pietersen from the home side. Finn insisted, however, that England's preparation would have been the same even had this week's turbulence never occurred. "It hasn't affected our approach. What we did on the first day, we would have done whatever had happened during the week. We would still have had the same intentions."

A power cut in the St John's Wood area of north-west London contributed to an early close of play, but the tourists would have ended the day with their mood brightening after recovering from 54 for 4 to 262 for 7 at stumps.

"Anything above 300 is a bonus," said JP Duminy, who made 61. "There is something there for the bowlers and if we utilise it, we can get stuck into their batsmen."