CREATE DATABASE UpdateStatsTest
GO
USE UpdateStatsTest

CREATE TABLE dbo.T (ID int NOT NULL)
ALTER TABLE dbo.T ADD CONSTRAINT PK_T PRIMARY KEY CLUSTERED (ID )
INSERT dbo.T(ID) VALUES(1)
GO

ALTER INDEX [PK_T] ON [dbo].[T] REBUILD
INSERT dbo.T(ID) VALUES(2) -- Insert one record between rebuild and updatestats
EXEC sp_updatestats

Updating [dbo].[T]
    [PK_T] has been updated...
    1 index(es)/statistic(s) have been updated, 0 did not require update.