The 26-year-old Cardiff forward has badly sprained ankle ligaments and may struggle to be fit for Wales's opening Five Nations' Championship game with France in Paris on 21 January.
However, Lewis's premature departure, and that of Wales's giant new second row, Derwyn Jones, with back trouble, did not unduly hamper the First Division leaders' progress at Brewery Field. Cardiff's fly-half, Adrian Davies, kicked 19 points while the visiting captain, Mike Hall, scored the last of their three tries.
Just before half-time, Simon Bryant, the Bridgend back-row forward, appeared to hurt his neck and lay motionless for several minutes before an ambulance arrived to take him to hospital. However, his injuries were less serious than first feared and he waslater discharged.
Cardiff still hold a four-point lead over second-placed Pontypridd, who edged to a 17-11 win away to struggling Pontypool.
In the CIS County Championship, Northumberland sit top of the Northern Group after a 17-8 success over Lancashire at Manchester while Yorkshire saw off Cumbria 25-18 at Morley to finish second. Warwickshire comfortably beat Staffordshire 30-3 in the Midland Group final at Coventry.
Scottish Exiles have emerged as the team to beat after two rounds of the McEwan's Scottish Inter-District Championship. Following last weekend's victory over the 1993 champions, South of Scotland, the Exiles won again yesterday, 34-13 against Glasgow at Murrayfield. Two of their tries came from the West Hartlepool scrum-half Derrick Patterson, who made his Scotland debut against South Africa, and the Bath No 8, Eric Peters.
In the Irish Inter-Provincial Championship, Munster appear to have an unassailable lead after beating Leinster 36-14 (their third consecutive victory). Irish Exiles, however, have that wooden spoon look following their 42-16 defeat by Ulster at Sale.Reuse content