Toyota's Ralf Schumacher will miss Sunday's US Grand Prix on medical advice after a puncture in Friday's practice caused him to crash.
Schumacher's Toyota is lifted off the track after the practice crash
He was taken to hospital after the crash and was warned by FIA medical delegate Gary Hartstein not to compete, so his place goes to Ricardo Zonta.
"Gary decided that the risk of having another hard impact within 48 hours was too much," said Schumacher.
The Toyota driver suffered a similar accident at the same track last year.
Zonta had been second fastest in the morning session behind Juan Pablo Montoya, who was fastest in both sessions, with Renault's championship leader Fernando Alonso third.
Reigning world champion Michael Schumacher posted the fourth fastest time in the afternoon session.
Briton David Coulthard was sixth fastest with a time of 1.12.076 for Red Bull while BAR's Jenson Button could only post the 15th fastest time in the afternoon.
Schumacher crashed at the banked final corner, the fastest section of the track, and his car spun, hit the wall and skidded across the track.
Last year he cracked vertebrae in a similar accident on the same spot, resulting in a six race absence.
Toyota team principal Tsutomu Tomita stressed Schumacher was being rested as a precautionary measure, and they did not anticipate such a long lay-off this time.
"After considering the recommendation of the FIA's medical team, we have decided to put Ricardo in the car for the remainder of the weekend," he said.
"We want to reassure you that this is a precautionary measure and we are confident that Ralf will be able to participate at this month's French Grand Prix."
Zonta was understandably low-key about getting the opportunity to drive.
"I'm glad to be back with a chance to race the car but on the other hand it's a very difficult situation," he said.
Schumacher was light-hearted about his lucky escape.
"Lightning is supposed not to strike twice the same place, but on this occasion I guess that does not apply to me," said Schumacher.
"I was approaching the last corner when I felt something go wrong on the left-hand side."
Friday's US Grand Prix second practice times:
1 J Montoya (McLaren) one minute, 11.118 seconds
2 K Raikkonen (McLaren) 1:11.228
3 R Barrichello (Ferrari) 1:11.746
4 M Schumacher (Ferrari) 1:11.758
5 N Heidfeld (Williams) 1:11.825
6 D Coulthard (Red Bull) 1:12.076
7 P de la Rosa (McLaren) 1:12.119
8 S Speed (Red Bull) 1:12.143
9 F Alonso (Renault) 1:12.265
10 J Trulli (Toyota) 1:12.344
11 G Fisichella (Renault)
12 F Massa (Sauber) 1:12.464
13 M Webber (Williams)1:12.578
14 C Klien (Red Bull) 1:12.664
15 J Button (BAR) 1:12.803
16 T Sato (BAR) 1:13.037
17 J Villeneuve (Sauber) 1:13.079
18 R Doornbos (Jordan) 1:13.361
19 R Zonta (Toyota) 1:13.567
20 P Friesacher (Minardi) 1:13.783
21 C Albers (Minardi) 1:13.963
22 N Karthikeyan (Jordan) 1:14.008
23 T Monteiro (Jordan) 1:14.336
24 R Schumacher (Toyota) no time