Van der Westhuizen, one of two South Africans in action in the third Diamond League meeting of the season, clocked 3:54.90 to improve his career record, set in Eugene, Oregon in June last year, by 1.36 seconds.
Starting slowly, the 25-year-old played catch-up for much of the race, but paced himself well to finish less than five seconds behind Kenyan Asbel Kiprop who won in 3:49.56, the fastest time in the world this year.
Commonwealth champion LJ van Zyl placed fifth in the men's 400m hurdles in 49.50 seconds - falling only 0.05 seconds short of his season's best set in Johannesburg in March.
World champion Kerron Clement from the US won the race in 48.12, equalling the second fastest time in the world this year.
Results at the third leg of the IAAF Diamond League series:
Men:-
100m Final (wind: +2.1 m/s):
1. Asafa Powell (JAM) 9.72
2. Richard Thompson (USA) 9.90
3. Churandy Martina (AHO) 9.92
4. Michael Frater (JAM) 9.97
5. David Kimmons (USA) 10.08
6. Lerone Clarke (JAM) 10.11
7. Jaysuma Saidy Ndure (NOR) 10.14
8. Martial Mbandjock (FRA) 10.26
800m:
1. David Lekuta Rudisha (KEN) 1min 42.04sec
2. Abubaker Kaki (SUD) 1:42.23
3. Marcin Lewandowski (POL) 1:44.56
4. Michael Rimmer (GBR) 1:44.98
5. Alfred Kirwa Yego (KEN) 1:45.14
6. Bram Som (NED) 1:45.21
7. Adam Kszczot (POL) 1:45.75
8. Thomas Roth (NOR) 1:48.79
9. Augustine Kiprono Choge (KEN) 1:50.03
1500m:
1. Manuel Olmedo (ESP) 3:36.98
2. Alvaro Rodrguez (ESP) 3:37.39
3. Yoann Kowal (FRA) 3:38.34
4. Thomas Chamney (IRL) 3:39.02
5. Nick McCormick (GBR) 3:39.76
6. Jermaine Mays (GBR) 3:39.84
7. Henrik Ingebrigsten (NOR) 3:40.14
8. Ricky Stevenson (GBR) 3:40.31
9. Mitchell Kealey (AUS) 3:41.47
10. Alex Kipchirchir (KEN) 3:41.55
11. Demma Daba (ETH) 3:42.05
12. Morten Velde (NOR) 3:53.80
Mile:
1. Asbel Kiprop (KEN) 3:49.56
2. Mekonnen Gebre Medhine (ETH) 3:49.83
3. Gideon Gathimba (KEN) 3:50.53
4. William Biwott (KEN) 3:50.75
5. Boaz Kiplagat Lalang (KEN) 3:52.18
6. Deresse Mekonnen (ETH) 3:53.52
7. Geoffrey Kipkoech Rono (KEN) 3:54.37
8. Peter van der Westhuizen (RSA) 3:54.90
9. Mohamed Al-Garni (QAT) 3:55.50
10. Juan Carlos Higuero (ESP) 3:56.71
11. Jakub Holusa (CZE) 3:56.75
12. Andrew Baddeley (GBR) 4:00.66
5000m:
1. Imane Merga (ETH) 12:53.81
2. Tariku Bekele (ETH) 12:53.97
3. Bernard Lagat (USA) 12:54.12
4. Lucas Kimeli Rotich (KEN) 12:55.06
5. Vincent Kiprop Chepkok (KEN) 12:56.32
6. Chris Solinsky (USA) 12:56.66
7. Alemayehu Bezabeh (ESP) 12:57.25
8. Mathew Kipkoech Kisorio (KEN) 12:57.83
9. Bekana Daba (ETH) 12:58.51
10. Leonard Patrick Komon (KEN) 12:59.15
11. Saif Saaeed Shaheen (QAT) 13:00.31
12. Edwin Soi (KEN) 13:07.70
13. Daniel Lemashon Salel (KEN) 13:08.23
14. Eliud Kipchoge (KEN) 13:09.89
15. Abera Kuma (ETH) 13:10.89
16. Yusuf Kibet Biwot (KEN) 13:15.33
17. Ayele Abshero (ETH) 13:18.38
400m hurdles:
1. Kerron Clement (USA) 48.12
2. Bershawn Jackson (USA) 48.25
3. David Greene (GBR) 49.05
4. Isa Phillips (JAM) 49.38
5. Louis van Zyl (RSA) 49.50
6. Justin Gaymon (USA) 49.56
7. Micheal Tinsley (USA) 49.70
8. Andreas Totsas (NOR) 52.87
Pole vault:
1. Renaud Lavillenie (FRA) 5.80 m
2. Malte Mohr (GER) 5.70
3. Aleksandr Gripich (RUS) 5.60
4. Michal Balner (CZE) 5.60
4. Przemyslaw Czerwinski (POL) 5.60
6. Derek Miles (USA) 5.40
7. Maksym Mazuryk (UKR) 5.40
. Steven Hooker (AUS) 0
. Alexander Straub (GER) 0
. Steven Lewis (GBR) 0
Shot put:
1. Christian Cantwell (USA) 21.31 m
2. Dylan Armstrong (CAN) 21.16
3. Tomasz Majewski (POL) 21.12
4. Reese Hoffa (USA) 20.69
5. Ralf Bartels (GER) 20.59
6. Pavel Lyzhyn (BLR) 20.41
7. Adam Nelson (USA) 19.91
8. Kim Christensen (DEN) 18.92
Javelin:
1. Andreas Thorkildsen (NOR) 86.00 m
2. Petr Frydrych (CZE) 85.33
3. Teemu Virkkala (FIN) 85.04
4. Tero Pitkmki (FIN) 84.43
5. Guillermo Martnez (CUB) 84.35
6. Ari Mannio (FIN) 83.81
7. Antti Ruuskanen (FIN) 83.45
8. Vadims Vasilevskis (LAT) 82.61
Women:-
200m (wind: +1.0 m/s):
1. Lashauntea Moore (USA) 22.38sec
2. Carmelita Jeter (USA) 22.54
3. Debbie Ferguson (BAH) 22.89
4. Aleksandra Fedoriva (RUS) 22.98
5. Cydonie Mothersill (CAY) 22.99
6. Sheri-Ann Brooks (JAM) 23.18
7. Ebony Floyd (USA) 23.20
8. Anneisha Mclaughlin (JAM) 23.37
400m:
1. Amantle Montsho (BOT) 50.34
2. Novlene Williams (JAM) 50.43
3. Debbie Dunn (USA) 50.75
4. Christine Ohurougu (GBR) 50.98
5. Lashinda Demus (USA) 51.09
6. Shericka Williams (JAM) 51.51
7. Denisa Scerbova (CZE) 51.62
8. Monica Hargrove (USA) 52.14
800m:
1. Anna Balakshina (RUS) 2min 01.65sec
2. Winny Chebet (KEN) 2:02.03
3. Cherono Koech (KEN) 2:02.28
4. Ingvill Makestad (NOR) 2:02.47
5. Celia Taylor (GBR) 2:02.57
6. Marilyn Okoro (GBR) 2:02.80
7. Ewelina Setowska (POL) 2:03.90
8. Susan Kuijken (NED) 2:05.22
100m hurdles (vent: +1.3 m/s):
1. LoLo Jones (USA) 12.66
2. Priscilla Lopes (CAN) 12.72
3. Perdita Felicien (CAN) 12.72
4. Danielle Carruthers (USA) 12.74
5. Delloreen London (JAM) 12.80
6. Christina Vukicevic (NOR) 12.91
7. Kellie Wells (USA) 13.00
8. Carolin Nytra (GER) 13.14
3000m steeplechase:
1. Milkah Chenos (KEN) 9:12.66
2. Gladys Jerotich Kipkemoi (KEN) 9:16.21
3. Lydia Jebet Rotich (KEN) 9:18.03
4. Sofia Assefa (ETH) 9:23.45
5. Violetta Frankiewicz (POL) 9:25.77
6. Karatzyna Kowalska (POL) 9:31.16
7. Ancuta Bobocel (ROM) 9:34.63
8. Elizabeth Mueni (KEN) 9:36.92
9. Sophie Duarte (FRA) 9:37.82
10. Karoline Bjerkeli Grvdal (NOR) 9:39.54
11. Ulrika Johansson (SWE) 9:53.63
12. Sandra Eriksson (FIN) 10:01.94
High jump:
1. Blanka Vlasic (CRO) 2.01 m
2. Chaunte Howard (USA) 2.01
3. Levern Spencer (LCA) 1.94
4. Ruth Beitia (ESP) 1.90
4. Svetlana Shkolina (RUS) 1.90
6. Irina Gordeeva (RUS) 1.90
7. Emma Green (SWE) 1.90
8. Stine Kufaas (NOR) 1.80
Long jump:
1. Olga Kucherenko (RUS) 6.91 m
2. Naide Gomes (POR) 6.78
3. Dariya Klishina (RUS) 6.77
4. Yelena Sokolova (RUS) 6.68
5. Ivana Spanovic (SRB) 6.65
6. Keila Da Silva Costa (BRA) 6.42
7. Margrethe Renstrom (NOR) 6.41
8. Carolina Kluft (SWE) 6.38
9. Brianna Glenn (USA) 6.36
10. Funmi Jimoh (USA) 6.20
Discus:
1. Nadine Mller (GER) 63.93 m
2. Zaneta Glanc (POL) 62.16
3. Aretha Hill (USA) 61.80
4. Yarisley Collado (CUB) 61.20
5. Nicoleta Grasu (ROM) 60.86
6. Sandra Perkovic (CRO) 59.71
7. Anna Soderberg (SWE) 58.47
8. Grete Etholm-snyder (NOR) 52.66