McGrath will see a specialist in Sydney tomorrow before deciding what to do, after struggling to play through the injury during his match-winning haul of 5 for 32 in New Zealand's second innings.
McGrath, who has now taken 162 Test wickets, said: "I'll just have to see what the specialist says." The team's physiotherapist, Errol Alcott, said McGrath had felt pain in the same part of his left groin operated on in May last year during hernia surgery.
The second Test, in Perth, starts on 20 November. Alcott added: "He can obviously bowl with what he's got and be effective - but it depends on what the expert thinks."
McGrath effectively ended New Zealand's last-day run chase by grabbing four wickets in 22 balls during the half hour before lunch, which reduced the Kiwis to 69 for 5.
New Zealand won toss
AUSTRALIA - First Innings 373 (M A Taylor 112, P R Reiffel 77).
NEW ZEALAND - First innings 349 (S P Fleming 91, C L Cairns 64).
AUSTRALIA - Second Innings 294 for 6 dec (G S Blewett 91, R T Ponting 73no).
NEW ZEALAND - Second innings
(Overnight: 4 for 0)
B A Pocock c Taylor b Reiffel 3
B A Young lbw b McGrath 45
N J Astle c Blewett b McGrath 14
*S P Fleming c Healy b McGrath 0
C D McMillan lbw b McGrath 0
C L Cairns b Reiffel 21
A C Parore not out 39
C Z Harris b Warne 0
D L Vettori c Taylor b Warne 0
S B Doull c Healy b McGrath 2
G I Allott lbw Warne 0
Extras (nb-6, lb-2) 8
Total (62 overs) 132
Fall: 1-4, 2-55, 3-68, 4-68, 5-69, 6-112, 7-115, 8-117, 9-126.
Bowling: McGrath 17-6-32-5 (nb1; Kasprowicz 8-1-17-0 (nb2); Reiffel 12-4-27-2 (nb2); Warne 25-6-54-3 (nb1).
Umpires: S Randell (Aus) and V Ramaswamy (Ind).Reuse content